Exploits

Xcom Exploits Readme

This page lists the exploits currently found within Xcom:Enemy Unknown and Xcom:Terror From The Deep.

The following categories primarily concern the first game in the series, Enemy Unknown, but can also be used with Terror From The Deep, unless noted.

Disclaimer: to do

ExploitsA

ExploitsB

ExploitsC

ExploitsD

ExploitsE

ExploitsF

To Do List

For writing up

• Destroying unique alien type/rank combos by way of transfering to a throw-away base with a containment + lab (nothing else necessary), starting research on the uniques, dismantling base completely. Repeat ad infinitum. Not exactly a very exciting exploit, but a useful one to know.

Exploiting Collision Detection

Wall Tile Trick

Most exterior diagonal and some flat UFO walls which occupy the entire tile have faulty boundary definition. A grenade thrown from outside the UFO onto one of these faulty squares will detonate inside the UFO. An unconscious unit thrown onto the same type of square from the outside will wake up inside the UFO once the stun damage has worn off.

Move Through Walls

If an agent is wearing armour which enables vertical movement (see Flying Suit/Mag-Ion Armour) and they are standing under a diagonal overhang, moving up one level will cause the agent to be 'inside' the wall. This agent can now move either way 'through' the wall. However, if an agent does not have flying capability, they can still move through walls if they are on a different level to the wall which you are planning on moving them through.
eg: if you're on a level above a UFO wall (eg: like a barn roof). Move your cursor to a point that is directly above the wall you want to 'stand' in (and eventually go through) and click the mouse button to make your agent move. The agent will walk off the edge, drop down a level (or more), and then step right into the wall. Once your soldier is standing in the wall tile, you can move into the UFO. You could also throw a primed grenade inside the UFO and then step out of the wall to the outside.

Large Units and Different Elevations

Large units use four map cells. The primary quarter, the part that has all the vital statistics and the first part to mind control, is the topmost quadrant (when viewed in tactical view) or the north-west quadrant (when viewed in map view). When moving such units up or down to different map levels (ie: elevations}, mainly via stairs or dropping it off the edge of a wall, the game only uses the primary quarter for collision detection.
WARNING There is a bug which is connected to this exploit. See it here: Faulty Large Units
This faulty collision detection enables large units to move up or down narrow stairs and ramps.

See Through A Ceiling

Agents standing on raised terrain (such as craft ramps, haybales, stairs), do not have a larger sight radius, however, standing on such elevated features raises the agents field of view. This can cause the head of the agent 'pop through' a ceiling and view the floor above when inside a room.

Throw Through Ceilings

All objects can be thrown up through ceilings to land on the floor above. To throw something onto the floor above (even if it that floor has not been scouted yet), just place your cursor on the level above and near your agent and 'throw'. The item or primed grenade will now be up one level (or more) sitting on the ground. Also, since explosions are confined to one level, your agent is safe from any damage from any explosions.

All Terror Missions During Daylight

At night, aliens have a visibility advantage over your soldiers. An Xcom agent can only see so far as the player. Aliens are not limited in any way from the darkness. The Aliens visible distance during a day mission is the same for a night mission. Xcom players obviously would want to do all their tactical missions during the day, however, during the limited time that a terror site is active, daylight may not be an option... not anymore!
When a Terror Site mission appears, save your game, then immediately launch your transport craft as per usual. Once your craft is in close proximty to the city under attack, you'll be able to see if the terror mission is going to be at night or in the day. If it is going to be dark then immediately make your transport craft patrol its current location. However, if you patrol for too long, then the terror site will just disappear and your score will suffer. Do not let the terror site disppear.
Terror Sites disappear on the hour BUT they will not disppear if an Xcom craft (of any sort) is targeting the mission. To take advantage of this fact. Only target the terror mission with your craft (any will do) when the hour changes. Patrol once again for the remainder of the hour, then once again target the terror mission just before the hour changes. If you do this, then you'll be able to stall for time until daylight.
Advanced Tactics:

• just after a terror mission appears, save your game and let the time pass by at a fast rate. You will see the terror site disappear on a certain hour. This hour is your time limit before you must do something to stop the terror mission from disappearing. Reload your game and try and work out when would be the best time to launch your transport ship to land in daylight hours. Remember, the act of targeting the site will now alter its expiry time. You can keep checking the time it disappears as long as you save/reload.
• if you guesstimate that you wil NOT win the terror site mission, DO NOT ignore it. Land at the site, then immediately abort the mission. Your score will be pathetic for that mission, but you do not get penalised for ignoring the terror mission outright.

Note: If you want to play every single mission in full daylight, use Scott T Jones's game enhancer, XcomUtil. Just remember that playing in full daylight does remove alot of the suspense. It is almost like cheating.

Grenades: Pass the Experience Trick

(Or who gets the experience when you "drop" a grenade)

Some commanders may have noticed that a soldier that drops a primed grenade rather than throwing it will often not get credited for the damage or killed enemies.

There is a very odd explanation for this. The game attaches an ownership to the grenades. It will rememeber who last threw the grenade so it can credit the right person with experience. Unfortunately, the game only assigns the ownership to a grenade after it has been thrown, but not when it's dropped or picked up.

So who gets the experience if its dropped? All X-COM owned grenades, at the very start of the mission, default to the very first soldier on the transport, or the very first armoured weapons platform if you have one. This means that if a grenade is dropped rather than thrown, all experience goes towards the very first soldier in the list, or the tank.

Can we move the ownership around and pass the experience to soldiers of our choice? Definitely! Just have the person you want to get the experience throw the grenade, then get someone else to carry and drop it to where it can be useful. Just remember to not throw it again.

The method of deployment for these grenades will be left as a practical exercise to the commander. Be creative, or be heartless - it's all up to you!

The biggest advantage of this unusual pass-the-experience technique would be to provide training for frail soldiers that would prove to be more of a detriment in combat than out of it - yet another reason for commanders to not sieve troops based on poor combat statistics.

Fire

Just how does it work?

NKF quick notes: (I might be duplicating something here, but I'm just jotting these down quickly before I forget)

• Fire does two types of damage to units. Impact and damage over time.
  • Damage Over time: Standing in fire or actually being on fire.
  • Impact damage: The weirdest and most unusual damage of all.
    • Anyone standing in fire: Receives hit-point damage every time an incendiary shell explodes
    • Anyone standing in smoke: Same as above, but take stun damage instead of hit-point damage.
• Fire does a fixed amount of damage. The damage of an incendiary weapon only determines how large the spread of the fire will be. So an autocannon incendiary shell is just as powerful as an incendiary rocket -- the only difference is the blast area.
• Fire and Smoke use the same object table, and being limited, can get used up very quickly and attempts at producing more fire or smoke will not work. Incendiary impact damage will still work on any units in fire/smoke.

JFG adds: Please see my Incendiary topic

Fog of War Scouting

The 3D cursor shows the terrain inside it, regardless of whether you have explored the tile or not. While the obscure shapes shown don't mean much to novice players, veterans will soon recognise tiles, and then the map segments they are native to. For example, you can easily find a UFO by looking for the destinctive wall patterns, and the power supply in the center. Or, you could use this to bombard locations such as command centers, or places you know aliens spawn at the beginning of play, with early Blaster Bombs.

Dead Man Switches

Grenades will only detonate when they are on the ground and when their timer has counted down. Timers will continue to count down regardless of location, but if the grenade is not on the ground, it will not explode. This means that you can set all the grenades to a time of "0" at the beginning of play, or at an earlier turn, and throw them when it's tactically feasible.

This is a double-edged sword, however, because should a unit fall dead or unconcious the grenade will hit the ground and promptly take out anything in the near vicinity... which may (or may not) work to your advantage. This tactic encourages keeping your troops far apart. If you anticipate the soldier will have a very high chance of being killed, it may be wise to use the "pass the experience" trick as described earlier before handing the soldier an armed grenade.

Proximity mines can be defused by saving, quitting the game, restarting it then reloading the game. You can still drop on top of them with a flying suit, or by dropping from a hole in the roof in order to safely pick them up.

Base Defence Mission Spawning Issues

If there are too many soldiers and/or aliens in too small a base, their initial spawning is unusual. Soldiers can spawn in the Access Lift and Hangars. Aliens can spawn outside the Access Lift and Hangars. Some lifeforms may not spawn at all.

Why does this happen? Each base facility has certain hardcoded spawn tiles. The Living Quarters, for example, have 8 spawn tiles, 7 on the lower level in an "H" pattern, and 1 on the upper level. Soldiers usually spawn at these spawn tiles, semi-randomly outside the Access Lift and Hangars. Aliens are assigned the spawn tiles within the Lift and Hangars.

But, if the number of soldiers exceeds the number of "friendly" spawn tiles, the excess soldiers will spawn at the "alien" spawn tiles inside the Access Lift and Hangars. Similarly, if the number of aliens exceeds the number of "alien" spawn tiles, the excess aliens will spawn at the "friendly" spawn tiles in the rest of the base. If there are not enough spawn tiles for the sum of soldiers and aliens, then some lifeforms will not spawn at all. Soldiers have higher spawning priority than aliens, so aliens will be the first to go (fail to spawn). All weapons and items will still be generated, though.

This can be exploited by garrisoning a base with so many soldiers that all spawn tiles are used up. Zero aliens will spawn (but their toys will still be generated), resulting in a bloodless victory and millions of dollars of loot!

A radar base with one Large Radar or HWD, an Access Lift, and one Living Quarters, can be filled up with 22 soldiers.

But if this is considered an exploit, then what is the "ethical" thing to do? To get all aliens to spawn properly at a radar base, you would have to go out of your way and build a hangar. This would in turn affect your defence tactics, and cost you money. If you don't build the hangar, you need to recruit at least 25 armed soldiers (with the accompanying Living Quarters and General Stores), or else a Sectopod or Chrysallid will probably spawn behind friendly lines. At that point, you could argue that the computer is the one doing the cheating, and 25 soldiers seems excessive for a radar base. On the other hand, you would be fighting a reduced number of aliens, since the Access Lift only has 8 spawn tiles.

Maybe you should just shoot down the scouts.

Base Facility	Spawn Tiles on Lower / Upper Floor
Access Lift	5 / 3
Hangar	15 / 0
Alien Containment	7 / 5
General Stores	7 / 4
HWD or Large Radar	5 / 1
Lab or Workshop	6 / 1
Living Quarters	7 / 1
Missile Defence	4 / 5
Defences (non-missile) or Shields	5 / 1
Psi Lab	7 / 3
Small Radar	0 / 2

Elevator Shielding

Due to questionable AI, aliens will not fire at you through an elevator (either up or down), even though they can see you and you can see them. When approaching elevators, have a soldier stand on it at the end of the turn, even if this leaves them with no TU. The aliens will not be able to come up/down through the elevator, keeping you safely shielded while you bring up rear troops and prepare for a floor breach. Additionally, soldiers may be able to see aliens standing at/near the elevator above or below them and can fire on them from the safety of their "elevator shield".

Milking Alien Bases

This experience training exploit relies on the "Elevator Shielding" exploit. When assaulting an alien base, your soldiers will be deployed at two staging areas with a 2x2 elevator in each one. Block all eight elevator squares with a soldier and wait for the fun to begin. Just keep skipping your turn and eventually, the aliens will find your soldiers and begin to congregate under the elevator. You can now shoot at them with complete impunity and can even pick out specific soldiers who need Accuracy training. When you see that no more aliens are appearing after a few turns, get your solders onto the evactuation area and leave. The alien base is intact for you to return for additional practice later. If you happened to kill everyone the base will be destroyed, so watch the timing of the alien movement phase and take care not to kill everyone. However, the alien leader or commander will almost always stay in the command center, so this is usually not a problem. For best results, arm your soldiers with pistols to maximize the number of shots they can take on each alien. Also, it is not recommended to attempt this tactic on a Sectoid base unless you are very confident of your soldiers' psi strength. As an extra bonus, you can collect alien weapons and equipment before evacuating.