From UFOpaedia
Jump to navigation Jump to search

General Comments

For now, we'll just say the smoke + incendiary stun effects only work on X-Com owned units until some tests can be run to confirm this. It's unusual that only X-Com units are affected, but the game has been known to surprise you even after you think you've worked something out.


Given how aliens love to hang around in a smoke-filled crashed UFO, IC rounds would be insanely powerful if they did actually work against aliens in smoke. I'm glad they don't seem to, as I'd be very tempted to cheat with it. They do work against aliens standing in fire, though, which is still quite cheaty...--Ethereal Cereal 21:35, 5 May 2006 (PDT)

I do consider the "standing on fire + new IC explosions = damage" a cheat. So I just don't abuse it. I only use IC rounds to illuminate or to finish off hiding aliens. It can also work as a "pass-through-and-die" tactic, the same way Proximity Nades work, although fire damage is pretty sad xD. --Nekrocow 00:36, 24 June 2012 (EDT)
I use it a lot in TFTD to clear out those island bunkers and the upper storage levels of the large train station. Either the aliens roast alive, or they come out. Otherwise yes, it's no doubt a cheat. Well, more a bug exploited as a cheat. -NKF 02:09, 24 June 2012 (EDT)

I just edited the Incendiary page a bunch, because Brunpal's Talk:Experience questions about Incendiary sparked my interest... I never did test IN vs. experience. It's a very good question if it turns out to cause Firing experience. But while reviewing this page, I had a number of questions, for anyone interested. Also, I only tried to clarify things, and don't know Incendiary well, so fix anything you know I got wrong:

  1. Did I get it right re: the set [ 0, 5, 6, 7, 8, 9, 10 ] for chance of initially catching fire? I over-wrote "linear" because it seemed odd when XCOM usually goes, e.g., 0-10. (Who tested this? - A little help here please. Just making sure.)
  2. Why flame a zombie unless it's near death (and how can you know if it is)? It's been a long time since I used fire - if you don't have flying armor, why mess around with a zombie by burning it, why not Heavy Plasma it.
  3. Any research/data on tile flammability versus duration of burning is appreciated. Probably it should go on the Terrain page byte, but be clearly referenced here. It's just a curiousity, but an interesting one.
  4. The last line of the page says "The damage values listed in the UFOpaedia do not determine how powerful an incendiary round deals damage; it only determines how wide an area will be blanketed with flames." Does anyone know IN strength vs radius, then? Should be easy to test and post.
  5. NKF, Zombie, or anyone else... would you mind seeing if Incendiary causes the Experience counter to increase? Brunpal is right that it's important to Experience... I found Stun Bombs to count for experience across their whole range, even if no stun damage occurred... if you have 11+ Mutons in a firing squad situation, passing around an Auto-Cannon with Incendiary may be better than standard pistols, depending on the range of the blast. I could test it, but it's been a long time since I've delved into the files; maybe one of you have them more close to hand. MikeTheRed

Offhand, the only way I could think of to check the remaining HP on a Zombie would be by using a Mind Probe. Given the relative uselessness of a Mind Probe after Psionics are developed, as well as the time needed to use the Probe once, this seems a rather impractical course of action, unless your Rear Commander has nothing better to do. I agree, Heavy Plasma on Auto is better. Arrow Quivershaft 20:33, 1 August 2008 (PDT)

  1. Yeah, the set is correct. When a unit is shot with an incendiary round, the game does a calculation to determine if the unit catches fire. If it doesn't catch fire, the unit takes no damage (the 0 in the set). If the unit does catch fire, it will take between 5-10 damage points. Stupid discontinuous range, but that's what happens. As you may guess, I did the Incendiary trials over at the StrategyCore forums in the Damage Modifier topic - see this post for the particulars.
  2. Why flame a Zombie? Simple. A Zombie which is killed by an Incendiary round doesn't turn into a Chryssalid. Zombies are easily outrun, so you can just keep picking at them from a short distance with Auto-Cannon Incendiary rounds and then running away. Fairly effective, even when your troops do not yet have armor to protect them. And when you do not have the luxury of the Heavy Plasma early in the game, Incendiary is a good way to avoid an overabundance of Chryssalids who are not so easy to kill. As for checking the Zombie's stats, you can only rely on the Mind Probe or Psi. Neither are available early either (the Mind Probe is usually low on the research tree for most people even though you can collect enough, and Psi is difficult to use as a soldier needs to be quite proficient to use MC.
  3. I have been meaning to do some tests in flammability vs terrain but only recently started fooling with MCD values. It'll be next on my list.
  4. Here, I uploaded a very recent spreadsheet containing both I and Smoke when damage values are hacked. See this file which contains both.
  5. I think I fooled around with Incendiary recently in conjunction with promotions. Soldiers who shot aliens with "I" didn't get promoted. Logically, that would mean the experience counter didn't increment. UNITREF.DAT would need to be checked to verify though. Addendum: indeed, as BB mentioned in the experience page (and a quick glance at the UNITREF.DAT experience counters by myself to triple-check my aging brain), Incendiary rounds do not increase any of the experience counters.

Hope this clears up some of the issues/concerns here. --Zombie 21:16, 1 August 2008 (PDT)

"The damage values listed in the UFOpaedia do not determine how powerful an incendiary round deals damage; it only determines how wide an area will be blanketed with flames. Fire is unlike other damage; it works at initial blast and then over time, as described above." and "Initial "impact" damage from incendiary ammunition is either for no points (unit does not catch fire), or between 5-10 points (unit catches fire)."

This should be stressed on ALL the various relevant pages. It's important. 6.4 dmg vs 90 dmg is a significant difference!--Brunpal 09:31, 2 August 2008 (PDT)

It looks like Incendiary is gaining some clarity (at least for me), thanks for starting it Brunpal...

  • The "6.4" was only for the initial IN round impact (set [ 0, 5-10 ]); it can then burn for 4 more rounds (set [5-10]). Perhaps a short way to state this complicated damage type is "Minimum 0 (unit does not catch on fire) OR unit catches on fire 1-5 turns, 5-10 damage/turn, 5-50 damage in total (average 21.5)". Does that look right, Zombie? I'm not sure where you got 90 from Brunpal...
90 is the listed damage from an IN rocket.--Brunpal 21:39, 5 August 2008 (PDT)
  • However, the numbers I just stated do not count possible additional damage from nearby terrain being on fire (as opposed to yourself). Maybe those should be included somehow. (And clearly, fire is much more dangerous outdoors than inside UFOs, where terrain does not burn.) But since terrain fire can last a variable number of turns, I guess you can't have a maximum damage. Average terrain damage from fire would be 6.5/terrain (1-12), but also, it can keep the unit itself burning more than 5 turns... hard to model.
  • Good point about flaming zombies, Zombie. I guess you ought to know, eh? :)
  • The spreadsheet looks great. Perhaps one of us can pull out the area patterns for non-hacked IN weapons and put them on the relevant pages. When it's done, the spreadsheet itself would be an asset to Incendiary (or maybe Damage, if it's listing all types of damage). As has been stated, it's the size (area) of the blast that actually directly relates to incendiary weapon "strength"... the diameters you found are probably what should be in parentheses next to weapon strength, although damage can appear as well.
  • Ok, no experience from Incendiary blasts. It might've been real interesting if there were, but it didn't occur to me to test. (Or maybe I tested it briefly so long ago that I forgot.) I would've guessed that they did, because the stun bomb and explosives do. Oh well.
  • P.S. Brunpal, we may not have touched pages in a year, but most/all of us have "Watch this page" turned on, so we get immediate notification of any pages we've edited or Watched. :)

-MikeTheRed 09:17, 5 August 2008 (PDT)

  • Sounds correct MTR. I think Brunpal was just comparing the "damage" (actually strength) of the Incendiary Rocket (90) to the average damage due to the "impact" of the blast (6.4).
  • Well, it isn't nearby terrain on fire which you have to worry about, it's the tile directly underneath a units feet which causes the most concern. If that tile is on fire and the unit doesn't move, it will take 1-12 damage points. While true that terrain on fire can last a variable number of turns, there is a definite upper-limit to how much damage a unit can possibly take. Fires don't last forever, and the combustibles eventually are consumed leaving either scorched earth or a damaged tile. Those damaged/destroyed tiles usually cannot be started on fire again by the spread of flames. They can only be set ablaze with incendiary ammo, and even then for only 1-3 turns (normal for dead tiles). So it's certainly possible to find a max damage. And for the most part, the things that burn the longest are usually objects, not tiles. And most objects you can't stand on anyway. But I totally agree that it's hard to model how fire functions due to the two forces at work: "impact" damage and damage due to standing in fire.

P.S. Some of us are actually around here and don't need to be coaxed back into existence by an email when a watched page is changed either. Just because it's quiet, it doesn't mean nobody's home. :) --Zombie 20:34, 5 August 2008 (PDT)

While understanding the whole formula for fire and fire damage happens is useful, it was not thinking to go that broad. I was just interested in what occurs from the moment a solider takes his shot, to the time that solider gets his TU back. ie damage from incendiary rounds vs fire damage. --Brunpal 21:39, 5 August 2008 (PDT)

It looks to me that, unlike all other forms of damage, Fire damage ignores armor, goes right past it. If so, this should be made explicit on the main page? Mugwump (talk) 05:55, 30 May 2021 (UTC)

Fire damage doesn't ignore armor - power suits for instance can't be damaged by fire, except if the unit is already injured. Read carefully the Damage section - there's a lot of nuances about how fire works. Hobbes (talk) 03:03, 1 June 2021 (UTC)
What I meant is ignore armor ratings for damage calculation. While accounting for the resistances listed on the Damage Modification page, doesn't incendiary act as if front, side, back and under armor are 0 for calculation? Mugwump (talk) 18:21, 1 June 2021 (UTC)

Incendiary vs Large Units

We're discussing this in Talk:Sectopod#Incendiary vs Sectopod, and a question came up. When an IN round impacts one segment of a large unit, presumably that segment gets the "Incendiary impact" function, i.e. 6/7 chance of catching on fire for 5-10 damage plus 1-5 turns of being on fire. Does the same "impact" function also apply to the 3 adjacent squares (6/7 chance), or is it just the "standing in fire" chance? If you had multiple regular-sized units standing in the area of effect of an IN round, they would each get "impact" effects (right?). So it seems logical that all 4 segments of a large unit, inside the area of effect, are also exposed to "impact" effects. But I wanted to check. Spike 06:34, 9 March 2009 (CDT)

Oh boy! Calculating this not only depends on a lot of unknown assumptions, but is fiendishly complicated - especially if you factor in the "funky fire" bug. And contrary to my noblest efforts, it's impossible to use IN weapons without inadvertently exploiting this bug. Even if you only fire IN at a single target until it's dead, once the target is "standing in fire" you effectively just can't miss.

Anyway back to the Large Targets specifically. The key assumption above is whether all regular-sized units in the area of effect of an IN burst are affected with "impact effects" - 5-10 dmg & 6/7 chance to catch fire. If they are, it's reasonable to assume the same thing happens to the 3 other segments of a Large Unit. However I suspect this is not the case, and strictly speaking "impact" effects should only occur at the single, impact square of an IN round. Testing needed!

More likely, the GZ+1 squares, whether occupied by small or large units, are only subjected to the "standing in fire" effects: 1/3 'catch fire' probability, and 1-12 terrain-based damage. And these effects are applied once per turn, not once per hit.

However, all of this is turned on its head by the 'funky fire' bug. After the first round hits, all units (and all Large Unit segments?) are "standing in fire". (Though maybe these fire damage routines run only for the "control" segment of the Large Unit? Possible, but unlikely.) Since they are standing in fire, the funky fire bug applies and all units/segments are hiit with "impact" effects.

So assuming a Large Unit is already standing in fire (e.g. from a previous IN hit or near miss), damage per IN round fired is 6.4 x 4 = 25.6 average, 10x4= 40 max. Subject to resistance/vulnerability modifiers, but ignoring armour level. In addition as multiple IN rounds are fired, the chance of all segments catching fire quickly approaches certainty. This not only means the Large Unit will sustain further damage at the end of the turn, it makes it impossible to escape the 'funky fire' trap by moving out of burning squares.

(Any testing needs to be very careful and probably only fire a single IN round per game, otherwise 'funky fire' will skew the results.)

So, in conclusion, the TU/kill factors I put up on the Talk pages for the Large Units (Talk:Reaper, Talk:Cyberdisc,Talk:Sectopod) should pretty much reflect the 'funky fire' reality after the first round connects, apart from the fact that you actually can't miss. The very first IN round to be fired would have the same effect (for immediate damage) on a Large Target as on a small one. But I really don't want to update the numbers to reflect this fact, it's just too awful. For AC-IN, the firepower factors will be about 6 times better than stated. Maybe I'll just remove them. :(

Spike 15:51, 10 March 2009 (CDT)

Simple Tests

I did a small number of tests and found some interesting results. In 5/5 tests, all 4 squares of the target (Reaper) were on fire the following round. (It's hard to tell if they are on fire the same round, as you need to extinguish the fire with smoke to see). Perhaps this makes sense, as it's a UNITREF attribute and so applies to the whole unit, not its 4 component squares?

Looking at the damage, it looks like "impact" and "on fire" damage applies to all 4 squares, i.e. x4 normal. Damage clusters tightly around 16-18 per hit which is roughly the expected value, maybe a bit lower (at x4). And since we are on fire, should expect an average of 7.5 ({5..10}/6) rather than 6.4 ({0,5..10}/7? Maybe something else is going on here, as these numbers seem a little low - 6.4 x 4 = 25.6 per hit or 7.5 x 4 = 30.0 per "on fire" hit might be expected on a Large Unit.

Drat. I didn't factor in the Reaper's 170% Susceptibility to Incendiary. So the actual damage levels are more like 10 per hit. Maybe there is no multiplier for the 4 squares? Hard to figure out what's going on here. In tests on hacked humans, armour level is not a factor vs Incendiary damage, otherwise I'd suspect the under-armour or something. 2.5 avg damage per segment seems too low. 10 average damage per alien seems too high - that should be the max, not the average. Is some mechanic pushing the average up to the max? I don't have a clue right now. Spike 06:53, 11 March 2009 (CDT)

The damage seems to be regardless of "funky fire" effect. A round fired at a target that is not burning / in fire seems to do about the same damage, per hit, as one that is in fire / on fire and so subject to the funky fire bug. So the only 'bad' effect of the bug is that you never miss, and you hit everything that is in fire / on fire. Not quite so bad, and it allows you to play honest by only ever firing at one target, not hitting any other targets by accident (!), and firing from point blank range so it doesn't matter that you never miss.

Burn Time was as high as 7 when multiple IC rounds were fired (on auto). Higher than we thought possible (1-5 range expected). However it sometimes goes DOWN after additional hits. Possibly the value is re-randomised with every new IC impact, but hits are cumulative while firing auto bursts?

Here's the raw test data:

Test 1. 
2 DH on Reaper, mix of auto and snap, some other IC impacts on others
Burn Time=7 - exceeds known limit of 5
All 4 sq on fire next turn
Is 'on fire' global? It's in Unitref, so maybe
Test 2.
1 DH on Reaper, only IC shot fired in game. 
In firing turn, taken 132/148 = 16 damage. Burn time=3
Start of T+1, taken 122/148 10 more damage, Burn time=2
T+1 Reaper shows all 4 squares burning
Test 3. 
Revisit #2 firing turn... fire another round (this will use funky fire)
So 2nd IC hit, 2nd rd fired, same target. 
Health now 114/148, further 18 damage
But Burn time has dropped to 2! Must re-randomise on each hit??
Maybe only accumulates during auto burst?
Test 4. 
Let's try lots of hits. Hack up accuracy to 255
OK 3 out of 3 hits on Auto
T+0 Health=98/148=50 damage (17 avg) Burn=6
T+1 Health=81 (17 more dmg) Burn=5  All 4 squares on fire. 
Test 5.
Revisit #4 and push to 6/6 hits
T+0 Health=41/148=107 (18 avg) damage Burn=7
T+1 Health=21 (20 more dmg) Burn=6  All 4 squares on fire. 
Methodology (Apart from Test 1) = only ever 1 (same) target in any IC AoE; no misses
(To try to minimise the impact of 'funky fire' effects - but can't eliminate)

Spike 23:27, 10 March 2009 (CDT)

I re-ran the same simple tests against a regular-sized (Floater) target instead. The results agreed much better with the 'standard model' of Incendiary effects. All results were within the permitted ranges in the 'standard model', though some values were unexpectedly. I think some variables to look for in Incendiary mechanics are:

  • Large Unit vs regular unit behaviour looks to be different
  • Auto burst vs single explosion looks to be different (maybe just due to funky fire bug, maybe not)
  • Tile MCD "time to burn" value seems to affect one or more of the other calculations / probabilities
  • Burn Time on the unit can go up as well as down. New hits seem to re-randomise the value.
  • End of turn processing does not always reduce unit Burn Time by 1. Can a terrain fire add to unit Burn Time?

Spike 21:25, 11 March 2009 (CDT)

I doubt a terrain fire adds to the time a unit is on fire. Actually, I'm quite positive on this since my tests from a while back were quite thorough. The counter can only tick down to 0, and when it does a terrain fire will have a chance of "reigniting" the soldier again.
Anyway, I had to start from scratch again on testing due to a few issues with my test scenario. I totally forgot that the first soldier on the unit roster is a bad choice for a "designated hitter" since he can never be automatically selected on a reload. Soldiers lower on the order are much better choices. So I got the shooting automated, but each reload was taking too much time since I had to reselect the shooter, select the shot, move the view down a level, shoot the target and abort. Having the soldier already selected cuts out 2 actions in the list allowing the script to run more efficiently. I'm going to try to get everything properly setup tonight, then start testing tomorrow morning. With a little luck and about 2 hours of babysitting the script to make sure it doesn't quit, I should have some prelims. --Zombie 21:55, 11 March 2009 (CDT)

Looking forward to seeing that data! I did some more testing just for the special case of Large Units, about 40 tests. My tentative conclusions:

  1. Damage range per 'impact' hit is the same as regular units, around 5-10 x Vulnerability (maybe + MCD Burn time?)
  2. Large units go on fire about 1/7 of the time when receiving a direct hit - as expected
  3. Either all 4 segments go on fire, or no segments go on fire - no 'part segments on fire'
  4. Unit burn times are not correlated with unit damage received
  5. Auto fire has the same average damage level per hit as snap fire
  6. Unit Burn Time can exceed 5, both on Snap and Auto. Highs of 6 (Snap) and 7 (Auto) were seen. Maybe 1-5 + MCD Tile Burn Time?

All my tests were done on the grid-lined pavement tiles from urban terror missions, which have an MCD default burn value of 2. For some of the "setting the large unit on fire" tests, I had the target floating in mid air, because air does not burn even during the turn that the IN round explodes - it makes it easier to see the unit burning.

From Bomb Bloke's editor notes, the 4 potential MCD tiles in a map location are: a North Wall, a West Wall, a Ground tile, an Object tile. All 4 of these MCD tiles might have a burn time value. But Ground and Object are the most likely to be relevant.

Spike 21:58, 12 March 2009 (CDT)

Ok, I got the script running and optimized it a bit to cut down some wait cycles. Right now it's cranking out approximately 400 trials per hour which is about as fast as I can make it go without removing some desktop icons (all the icons have to refresh at the end of each logging cycle which takes a little time). Anyhow, just for giggles I stopped it after 400 trials to get some prelims.
If you average the percent columns, it comes to 14.28571429% while the expected is 1/7 or 14.285714285714285714285714285714 which is a difference of 4E-09. This means 400 reloads is plenty enough values for this application. Great news! Well, as you can see, instead of the set [0, 5, 6, 7, 8, 9, 10] for MCD of 1, this scenario where the MCD was 0 is shifted up by one [1, 6, 7, 8, 9, 10, 11]. Interesting.
Tomorrow I'll rerun the MCD 1 scenario again to verify the values and damage set. Then it's on to the MCD of 2. --Zombie 01:50, 13 March 2009 (CDT)
Extremely interesting! By the way, it was probably a late night but - the average any 7 numbers that (must) add up to 100% is always going to be 1/7th of 100%, so that result doesn't really demonstrate any confidence in the data. It would be the same with one result, or with a trillion results. The 4E-09 discrepancy is just the precision error in your calculator/spreadsheet's calculation of the percentages and the average of the percentages. You've got some considerable variation from 1/7th on the individual numbers, I'm not sure if that's just to be expected with only 400 trials. But for example "0" and "10" are both a bit high so it might be non-linear (probably not). Anyway we'll see when all your results are in! (To measure the degree of variation from the expected result, what you want is a chi-squared test or something - and I don't know what I'm talking about there so I'll shut up!)
I'm checking Bomb Bloke's MCD database, and there are some tiles in there (U_BASE 22-25) with MCD burn value of 30 - I might play with those and see if anything dramatic happens. Oh except looks like they can't be set on fire (255 flammability). There are others that are quite high (8-), and still flammable. Or I could hack an MCD file (scary). Maybe I'll just wait for your results Zombie! Spike 05:49, 13 March 2009 (CDT)

Incendiary Research

Large Units On Fire

Here's another interesting test for setting Large Units on fire. Set AC-I power down from 42 to 1. At this IC power, there is no area effect. You can't even start a fire on one tile. All you can do is set units on fire with a direct hit. This means there is no way the other 3 squares of the Large Unit are in the IC area of effect.

Result: Whether you hit a one square regular unit or a 4-square large unit, if it goes on fire, all squares of the unit still go on fire. Along with the fact that the inflicted IN damage level vs Large Units is basically normal (see above), this tends to confirm that being on fire is a "unitref" property and, unlike HE and Stun Bombs, is not applied (multiplied) vs the number of squares the unit occupies. (In fact it would be good to check that HE is actually applied separately to each square, with different HE strength, potentially different armour facing, etc. Maybe the engine just simplifies things and multiplies damage by 4?)

Spike 07:56, 15 March 2009 (EDT)

Unit Burn Time

Unit Burn Time seems to be considerably cyclic rather than random. Very often, it just steps down by one from the previous value. I suspect this is because the "impact" routine calls the "end of turn" incendiary/smoke routine (see User talk:Seb76#Incendiary Bug). Sometimes it does not happen, maybe because some other factor has caused the Burn Time to increase.

Here's some data. This was done against a Reaper with AC-I power set to 1 (and 10% TU Snap fire cost). But I've seen similar results with standard AC-I.

Hit	H/H	Dmg/Avg	Burn Time
1	137/150	13	2
2	126/150 11	1
3	104/150 22	0	Very high damage (=13x1.7). Unit not on fire when game restored.
4	 96/150  8	7
5	 81/150	15	6
6	 66/150 15	5
4,5,6	 76/150	/9.33	5	(Auto) 9-10 (=5-6x1.7) is near minimum dmg
7	 56	10	4
8	 48	 8	4	What happened here? didn't cycle. MIN dmg (5x1.7).
9	 35	13	6
10	 25	10	5
11	 10	15	6	New shooter takes over
12	  2	 8	5

Spike 07:56, 15 March 2009 (EDT)

You're right on spot once again ;-) When a unit takes a direct hit from an IN round, it is set on fire (the duration is randomly chosen between 0 and incendiarydamagemodifier/20). Then the "end of turn" routine is called, which inflicts damage *and* decreases by one the number of turns to be on fire (done for all units). Then it sets on fire units standing in blaze. The duration is calculated as for direct hits; if the unit was already on fire, it'll take the maximum value between the new value calculated and the current value affected to the unit on fire. Not sure it is readable but I think you'll sort it out ;-) Seb76 10:51, 15 March 2009 (EDT)

Incendiary in TFTD

I read somewhere there are reduced effects underwater (or enhanced effects on land) for TFTD Phosphor rounds. I couldn't find an exact statement of the quantitative difference - does anyone know this? Spike 14:53, 9 March 2009 (CDT)

The effects of Incendiary weapons underwater (or Phosphor, as TFTD refers to it) is halved over the UFO equivalent. Incendiary weapons are doubly effective on the surface(Terror Missions) vs underwater, but of the three weapons that can fire Incendiary, two of them(Torpedo Launcher and Hydro-Jet Cannon) can only be reaction fired on land. The Gas Cannon can be fired in eiither location. Arrow Quivershaft 15:08, 9 March 2009 (CDT)
It's clear that the effect underwater is half the effect on land. But does the base level (in USOPaedia / OBDATA) refer to land use or underwater use? Spike 15:13, 9 March 2009 (CDT)
As I recall, the base level is on land. The numbers for Phosphor ammo are close to the UFO Incendiary damage numbers, but I know it spreads less underwater. Arrow Quivershaft 15:15, 9 March 2009 (CDT)
Look at the (puny) area effect pattern sizes underwater, that sounds about right. Can anyone confirm this? Spike 15:40, 9 March 2009 (CDT)

There is actually no difference between the pattern for the Gas Cannon's P rounds underwater as on land. Both have a r=3, d=7 pattern. (CE version at least). Maybe the pattern is smaller the deeper you go? --Zombie 16:45, 9 March 2009 (CDT)

OK now I'm really confused then! (I realise I was getting confused with the Dye grenade's small footprint vs Smoke grenades). If the blast pattern is the same size, that implies the weapon power is unchanged. So in what sense is Phosphorus "half as powerful" underwater? Does it burn half as long? Is the impact and fire damage halved? Spike 16:49, 9 March 2009 (CDT)

I really doubt the damage to units would be affected if the power of the round was modified. The power of the round only determines the size of the pattern produced, not the damage inflicted to units. I'll have to check the burn times and spread rate but my thought is that the two are identical in the version I'm using. Like I said, the pattern may get smaller the deeper you go underwater. The pic above was for a shallow site. It'll take a while for me to find a deeper site to check it out, otherwise some editing of the game files may be necessary to force the scenario.

I just checked the Dye Grenade underwater and on land. Both produce the same r=1, d=3 pattern. So yeah, they are really pitiful when compared to the Smoke Grenade.

Don't really go for the use of "impact" damage with Incendiary/Phosphorous rounds. There is no real impact since the damage range is discontinuous. The unit either catches fire from the splash of fire (in which case it does 5-10 damage points), or the unit doesn't catch fire and the unit remains unharmed. If there were such a thing as impact damage, the range would be continuous like normal weapons, in this theoretical case it would be [0-10] inclusive (ie the set [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]. --Zombie 17:36, 9 March 2009 (CDT)

Anyway, the half thing came up because AQ was comparing TFTD to UFO, not comparing the effects in TFTD from underwater and on land. However, further comparisons reveal that a hacked HC-I round of 60 produces the same pattern as a GC-P/60 round. Perhaps this whole dilemma can be traced to the Dye Grenade? --Zombie 18:28, 9 March 2009 (CDT)

That's entirely possible the Dye Grenade is the source. However, several of the pages for the TFTD weapons state that Phosphor is far weaker in water, so I didn't check. My mistake. Arrow Quivershaft 19:35, 9 March 2009 (CDT)

Thanks for the feedback everyone. So this could just be a recycled rumour? I guess the general assumption is that the game engines are identical, so we would want evidence that TFTD is different. Looks like Zombie has proved that the area effect is equal (at least at shallow depths). That leaves only the fire damage or fire duration. Testing that would require repeated observations to check if fire damage is less than 6/hit, less than 6/turn, and burning for no more than 2-3 turns. Spike 20:14, 9 March 2009 (CDT)

As with any wiki where contributions can come from anywhere, there are bound to be problems with validity of the statements made. So unless those statements are backed up by real-life test data instead of memory or hearsay, take them with a grain of salt. The other point is to avoid spreading disinformation at all costs (I have been guilty of this as well, but try to at least quantify them). So there you go. I'm still trying to get a deeper underwater mission to check the size of the pattern produced there. Checking the spread of flames or damage inflicted to units shouldn't take too long though. I'll see if I can't get that done tonight yet. --Zombie 20:23, 9 March 2009 (CDT)
Ok, I ran some trials with an unmodified GC-P round on the normal seabed floor against soldiers having 100 health and 0 all-around armor. For the guy standing at GZ, I saw ending health values of 99, 94, 93, 92, 90, and 89 (n=50). So that comes out to 1, 6, 7, 8, 10 and 11 points of damage respectively. I didn't think 11 damage was possible. Here's where things differ though. All the other guys who were clustered around GZ always received only one point of damage, never more, never less. In EU, the guys around GZ took damage equal to the guy at GZ. Odd. So then it occurred to me that perhaps I should check the MCD values of the seabed (TFTD) and the desert (EU) landscapes. Both are basically identical in terms of armor. But the seafloor has a "time to burn" value of 0 while the desert has a value of 1. So maybe our understanding of normal fire isn't totally complete. I'm going to go back to EU and retest the desert landscape with varying MCD burn time flags to see how that affects damage. ;) --Zombie 23:00, 9 March 2009 (CDT)
The whole Phosphor being half effective under water is related to the burn time and spread, if I remember correctly. The settings in the MCD files may be the culprit. The actual damage dealt or initial spread may not necessarily be affected.
Hey, I just had a wacky idea. XComutil. Use its feature where you can set the depth of a mission. Launch a mission on a island terror site map (again, use XComutil's map picker to get to this faster). Lots of grass to burn there. Set fire to it and count how many turns before the fires die out. Redo the test, but this time set the depth to a deeper level. Try the whole process out again.
Next repeat this with one of ye-olde seabed maps. They look really weird without the blue palette shift when played on land, what with the landscape being gray.
It's possible that the half-effectiveness relates to the fuel that the fire has to burn more than anything else. Further confirmation on how long the flames stick to a target when on land or underwater may be helpful. -NKF 01:28, 10 March 2009 (CDT)
I've been burned one too many times using editors or utilities to mess with saved games. Half the time they introduce some unknown "feature" which isn't documented. Thanks, but no thanks. I only test with an unmodified game, except for the changes I make myself to keep control of the situation. Anyway, I tested a patch of fire on the seabed to see how long it remained lit (which has a "time to burn" value of 0). It only stayed lit the current round the shell detonated. After that the fire went out. So this agrees with what is expected. Will continue to work on this as I get time. --Zombie 01:51, 10 March 2009 (CDT)

Well, I suppose my recommendation doesn't necessarily need XComutil. It would've certainly made it easier. But yes, it does introduce a few things that work behind the scenes that we might not know too much about. However, if I remember correctly, one of the battlescape savegame files should hold the depth level of the current map you are playing on. All you'll need to do is tweak that to change the depth of the map.

One other thing, the different effect HE has on the same tiles underwater and when on land (ala the Triton) may also be one of the other culprits behind the belief that phosphor is less effective on land. Being able to blow up the Triton on land, but have it appear virtually indestructable when underwater does that. -NKF 01:59, 10 March 2009 (CDT)

re Zombie's underwater tests, there is normally (i.e. on land in EU) a difference between the IC damage on the target of the direct hit, vs lower damage to others in the area of effect (hmm contrary to my IC kill modelling assumptions: uh oh I may've spoken to soon). But only seeing 1 damage on the others in the AoE does seem low. We need to figure out why. Did any of the other targets catch fire? Does that ever happen underwater? Do tiles ever burn past the turn when the IC round is fired? Any of these factors would reduce total fire damage/effectiveness by more than half. Actually, doesn't it say the 1-12 damage for "in fire" is not random, but dependent on terrain type? That could be the answer.

The Incendiary article actually mentions 4 modes of fire damage, only 3 of which are quantified:

  1. "impact",
  2. "being in fire"
  3. "being on fire"

The 4th mode is "damage from burning terrain. Only a tantalising mention is given, no quantitative details. This could be the source of the discrepancy. In fact it might be a component of "being in fire" that's not fully understood. I think Zombie is right to review the assumptions on this one - nice work! Spike 04:05, 10 March 2009 (CDT)

As I recall, "damage from burning terrain" is synonymous with "Standing on a tile that's currently on fire." Thus "Being in fire." But that's me and I'm tired this evening, so I could be wrong. Arrow Quivershaft 05:30, 10 March 2009 (CDT)

I performed my TFTD Phosphorous tests underwater and after the flames died out some of my men did catch fire. So this part seems to jive with that of EU. Tiles do not burn longer than its "time to burn" value in the MCD files. So for instance, in the seabed underwater testing mission, the tiles have a MCD burn value of 0 which corresponds to the results seen (ie fire didn't stick around into the aliens turn or X-COM's next turn either, it only stayed lit the turn it detonated). There really is only 2 "modes" of I/P/fire damage:

  1. The code used for determining if a unit catches fire: 0 damage (if the unit didn't catch and was able to shrug it off) and 5-10 (if the unit catches).
  2. Standing in fire.

At least from the initial tests in TFTD, units outside GZ are just considered to be standing in fire that turn and always take 1pt of damage. Anyway, I don't want to talk myself into a hole without doing more tests. All the following trials I do will be in EU to hopefully curtail any unknowns in TFTD. Once EU's code is figured out then it can be applied and compared to TFTD. --Zombie 09:06, 10 March 2009 (CDT)

If they are "standing in fire", do you think the 1pt damage/turn is based on the fire characteristics tile/terrain type they are standing on? Is it more generally 1-12/turn, dependent on terrain? Also if you get a chance can you test large units and see what kind of effects they take on the GZ+1 squares? If the GZ+1 squares of a large unit are just 'standing in fire' rather than 'catch fire/5-10 impact damage' this will substantially weaken IC vs large units. And I will have shouted too soon! :) Spike 09:18, 10 March 2009 (CDT)

I did some ad-hoc tests in TFTD. Actually I just ran around firing GC-P and HJ-P rounds everywhere. :) On a typical seabed layout, I found that most things don't burn - the fires don't last into the next turn. The only things I could get to burn were the green moss stuff and and coral skeleton "trees". Even the barrels do not burn. Also, I did not see much sign of terrain damage caused by the fires. But the moss and coral did burn for the normal period, i.e. 1-5 turns.

I also managed to kill an Aquatoid with a single direct hit from a GC-P, in one turn. He died at the end of my turn or the start of his. That seems unlikely. 5-10 from being hit, plus 1-12 for standing in fire, plus maybe another 5-10 from being on fire? It's just about possible I suppose, to max out near 32 damage (if the terrain offers you "12" when it burns). Anyway those are my unsystematic enquiries. I have the 8 save files of various stages of the battle if anyone wants to take a look. It was from a virgin TFTD installation and there was no editing or jiggery pokery.

OK I've uploaded the save files File:TFTD Incendiary Tests 01 and taken a look myself with BB's editor. Prior to being hit (Game_4) our Aquatoid was in rude Health, 30/30. Immediately after being hit (Game_2) he was at 19 Health (no Stun damage) and On Fire, as well as Standing in Fire. That implies 11 Damage from the "impact effect" which is not supposed to happen. As noted, at the end of the same turn or beginning of his next turn, he dies. He looks to be standing on a standard seabed square, just sand, the kind of thing that does not burn. He is next to some of the brown cushion-like coral, but I don't think that burns, at least not over multiple turns. In fact in the same turn he is hit, at the end, you can see him dead (Game_3). Since there was only one alien, he died in the same turn. OK that's slightly confusing, maybe someone can double check the turn numbers in the save files (don't know where they are).

Spike 13:29, 10 March 2009 (CDT)

Doh. I is a idiot. The Aquatoid was killed by the incendiary fire bug - I fired extra IN rounds at terrain objects after he was on fire. Which explains why he is already dead by the end of my turn. Spike 15:08, 10 March 2009 (CDT)

Yeah, you gotta watch that. Well, anyhow, I edited the desert landscape in Enemy Unknown to have the same MCD "time to burn" value of 0 as the seafloor in TFTD. From the limited tests, the results look the same as in TFTD. (Fire burns out after the initial turn it detonated, units around GZ taking 1 unit of damage while the guy at GZ got more). So that means I can focus my efforts on EU with little worry because there will be no issues. I'm going use BB's logger and AHK to automate the data gathering aspect to save me a bunch of time. I'll probably need the full requisite 2000 reloads though, as the guy at GZ is not the same as the 24 soldiers around him. Wish me luck. :) --Zombie 15:54, 10 March 2009 (CDT)

Good luck! I just read the MCD article, and it mentions 2 fire-related byte fields in MCD - "likelihood of catching fire" as well as "time to burn". Is the last field variable or fixed? Could the first field determine the damage/turn to units when it's on fire? Also with a possible 4 terrain items that could all be burning, is the maximum damage higher than 12? Spike 16:10, 10 March 2009 (CDT)

Offset 45 is the flammability rating of the tile. This most likely controls whether an adjacent fire will spread to the tile in question. (For instance, if a fire is burning and the next tile over is a tree or something, it'll probably spread there fast because of the combustibles present). The other byte is offset 57 which is the one we are after. Don't know about the 4 types of things which can exist on a tile at once. I think the most I have ever seen is 2 (usually ground and a wall). Wouldn't hurt to edit a tile to include all 4, but that's an entirely different test to do. It'll have to wait until we get a better understanding of basic fire. ;) --Zombie 19:38, 10 March 2009 (CDT)
Here's a question. On Large units, if only one segment of the Large unit is on fire, will the fire spreading code allow the other three segments to catch on fire? Arrow Quivershaft 20:13, 10 March 2009 (CDT)
I highly doubt it. Unit fires are completely different creatures from terrain fires. Needs testing though. --Zombie 20:55, 10 March 2009 (CDT)
Yes it would have to be a very special case, since afaik fires do not spread from regular units on fire to adjacent terrain or to other adjacent regular units. Though it would make more sense than any of those things. Spike 21:03, 10 March 2009 (CDT)

Incendiary Bug

(Also known as the Funky Fire/Smoke bug.) I made some suggestion about why this bug happens, and how the code could be patched to fix it: User talk:Seb76#Incendiary Bug. Spike 07:13, 12 March 2009 (CDT) Here is the general discussion of the bug:

With this 'Funky Fire' bug, presumably what is going on is that during an Incendiary explosion, the game engine loops through all units that are in fire(and on fire?). This is wrong. What it should be doing is testing to see if they are within the Area of Effect of this particular IN round. The game definitely has working code to correctly select units within an area of effect, since that's what happens for HE and Stun explosions. But in this case it does not apply the correct selection criteria. What is looks like it does is scans the Unitref table (copy in memory) for every unit standing on a tile with fire in it, and maybe also with the 'on fire' flag set. Both of these lookups are actually irrelevant to an exploding IN round. These looks would make exact sense for the end-of-turn processing of fire damage, but not for the instantaneous effect of an IN round. They should use the HE/Stun routine instead, to select the units for processing. Then when the units are selected, it should apply the IN effects - still to be determined. So yes, I think what's happened is the coders mistakenly used the "end of turn" criteria to select units for instantaneous damage/effect when an IN round explodes. I guess one difficulty is that the HE routine is performing 2 functions - it's doing damage to terrain, and also flagging units to apply damage to. It may also be setting smoke. Similarly, the IN routine ought to have 2 functions - to apply fire/burning time to the tile, but also to apply IN damage effects to the occupants of the tiles. This really could be coded badly and just hard to fix. Spike 19:17, 11 March 2009 (CDT)

OK I'm pretty sure this is the whole problem with the Funky Smoke/Fire bug. What's going on is the Incendiary Explosion routine is calling the whole end-of-turn smoke/fire processing routine, every time an IN round explodes anywhere on the map. That's why you get smoke induced stun as well as fire-induced damage. All you need to do is find this IN Explosion routine and make it return unconditionally before it calls the end-of-turn routine. That will substantially solve the bug. What the IN Explosion routine ought to do is:

  1. In area of effect
    1. add fire to tiles
    2. possibly do 33% check for units to catch fire - unless this is performed by the end of turn routine (probably)
  2. IF a unit was hit directly
    1. check to see if it catches fire
    2. possibly do "impact" damage.
  3. Return, without calling the end-of-turn smoke/fire routine

And it's entirely possible there was never supposed to be any "impact" damage, all that was intended was to set tiles and units on fire, with any damage only coming at the end of turn. You can easily imagine a last minute and ill-considered coding decision to run the end of turn routine upon every IN explosion, as an attempt to increase IN lethality, without thinking through the implications properly. So the "impact" damage could just be a side effect of the funky fire bug - applying the 5-10 "on fire" damage right away, when it was meant to be applied at end-of-turn.

Spike 22:11, 11 March 2009 (CDT)

Hey, that's a nice piece of supposition:) There is actually what I called an ApplyFireAndStunDamage function which is indeed called after IN explosions and at the end of the turn... It basically damages/stuns every unit on fire/in smoke and makes units standing in firing tiles possibly take fire. The function is called 5 times, one of which is at the end of the turn so patching the 4 other locations should remove the bug; but also weaken the IN rounds...Seb76 16:22, 12 March 2009 (CDT)

I also suspect that other "end of turn" processing happens with every IN round fired. I am pretty sure "fire spreading" checks occur, as I have seen fire spread when using perfectly accurate shots. Either "fire spreading" happens, or there is a random element in incendiary area of effect, that is definite. I want to repeat these tests to see if "catch on fire" effects also happen for those who are standing in fire when an IN round is fired. Spike 08:59, 31 March 2009 (EDT)


Was exploiting the Elevator Shield trick on an Alien Base Assault, and I had the forethought to pack lots and lots of Incendiaries. My sick sick mind found it amusing to set all those aliens on fire and watch them roast stupidly and helplessly. (Jasonred)

Fire Damage

(moved from talk:UFOextender)

Not sure if the bug is already posted. And Not sure if I should post the bug here or in Talk:Incendiary. Problem is if you use extender to fix funky fire bug. Incendiary no long does any damage at all. Units only take the small amount of damage after ending turn because they're on fire. Using 1.28.3 extender

To test this. I stripped a soldier of armour. And pounded four incendiary rockets into the soldier in the same turn. No damage. And then next turn, his health drops a little because he's standing in fire. This may not be a problem for most players. But it is still a major bug. I understand the funky fire problem is already difficult to fix, and I say thanks to all who will try to help solve this bug. Hellblade 14:44, 28 September 2012 (EDT)

That's not a bug, that's the fix. Incendiary damage is only applied at the end of the turn. Think about it... does fire kill faster than a bullet? Faster than a grenade? Can you kill someone with fire faster than they can get a shot off back at you? No, to all these things. To compensate for fixing the bug, fire damage is doubled compared to the previous end-of-turn fire damage (that always existed). It is no longer applied per shot or per impact. All you get "per impact" is another chance to set the target unit itself on fire. Incendiary is a weak attack. It has the benefit of a wide area effect, no HE block, and ignores armour. There are situations when IN is the only effective weapon XCOM possesses. But, like everything, it has strengths and weaknesses. Spike 15:51, 28 September 2012 (EDT)
I see your point but let me elaborate. Heat, not fire, do kill as fast as bullets. The original game mechanics separated heat from fire just as in real life. It intended to have the big heat blast damage first and then the small fire damage per turn.
Take the most extreme case, napalm or volcanic lava, you get fully cooked in less than a second - just by heat alone, and you may/may not catch fire later on. And heat blasts travel as fast as bullets, in some cases as fast as light. I believe the game has different Incendiary damage values to do different damage according to how strong the heat is, not the fire afterwards. The damage by fire later on makes sense because natural burning fires aren't that hot comparatively.
I understand the difficulty in trying to fix this. But before this fix you could kill a reaper by a few AC-I shots (which is their weakness) and now you can empty the two clips at it and it'll never die. Hellblade 03:11, 4 October 2012 (EDT)

Advantages/Disadvantages of using Incendiary for nighttime light

It seems for most folks that electro-flares are the go-to for night lighting and incendiary rounds are a distant afterthought. With that in mind I propose this list of pros/cons to using incendiary at least as a major complement to flares. I believe most people today are playing with OpenXcom or something that fixes the bugs, so I'll trim this of factors arising from bugs/limitations

What you believe might be completely off the mark since the original game is still being sold on Steam and new players will play that before even trying OpenXCom. The deciding factor should be that this page is in the original game section, thus it should reflect the original game and its bugs, not one open-source clone that people might have never heard of it before. If you're writing a page for the OXC section, then the original bugs shouldn't be mentioned but you're writing for the original game. Hobbes (talk) 18:08, 15 July 2021 (UTC)
Also, deleting someone's contribution just because you disagree with it isn't exactly how wikis should work. It should give the player as much information as possible, then let him/her decide what to do it with. And if there are different opinions relevant to the matter, then they should be contrasted together and the article should be written to reflect both. Wikis should be inclusive, not exclusive. Hobbes (talk) 18:16, 15 July 2021 (UTC)


  1. Low damage, and for each soldier with incendiary rounds loaded they can't attack with more effective weaponry unless
    1. they unload and reload
    2. they carry another gun or use 'nades/stun rod
  2. Not re-usable, will always be depleting stock
  3. Shooting IC rounds doesn't generate experience/training like throwing throws does for throwing accuracy


  1. Not dependent on throwing limitations of range and arc/trajectory
  2. Very efficient in terms of light-output per weight, storage space, and time units
  3. Can set area on fire to illuminate where the enemy is initially, then as the fire burns out you may move into the cover of the smoke it generates
  4. Does at least some damage to enemies - very unlikely to kill them, but softens them up so future attacks more likely to neutralize
  5. Area denial - fill a small building or enemy craft with flames and watch them flee out into your reaction fire, or at least out where you can get them, they don't get the drop on you
  6. At least in OpenXCom the enemies on fire should provide lighting, helping to spot them at a distance
  7. Fire is less vulnerable to being destroyed by nearby explosions, unlike those wimpy flares. And even if it is snuffed, it isn't something you were counting on re-using
  8. Reaper vulnerability
  9. Zombies not re-spawning to 'lids when KO'd by fire splash
  10. You can dedicate a few number of soldiers to throwing fire around while the rest keep their hands and TU's free to attack
  11. Soldiers that go berserk/get MC'd can't hurt armored soldiers w IC fire

Now it seems to me that the first Con is major and obvious, but the many Pros are overlooked. Also that big Con could be greatly mitigated by cannon wielders w incendiary carrying a decent secondary weapon: thinking plasma rifle or pistol, laser pistol

any I'm missing? what about putting this on the main page? (also I meant to make this a main topic, not sub-topic of the above) Mugwump (talk) 00:09, 9 July 2021 (UTC)