A large improvement over the Stun Rod, the Small Launcher and its Stun Bomb are unique in the XCOM arsenal. It is a fired weapon which can knock units unconscious if they are caught in its blast. For more on reviving units, see Unconscious and Medi-Kit.
The Stun Bomb uses the same projectile and explosion graphics as the Blaster Bomb, which gives every commander a moment of sheer terror - Then delight, to find it was "only" a stun bomb. Stun bombs do not use waypoints, and leave no explosion damage. Thus, it is easy to distinguish between the two.
Stun Bombs never cause Fatal Wounds. One less thing to worry about. However, if a Soldier already had a Fatal Wound, note that they will continue to lose health while unconscious, and can even DIE. So if there is any question in your mind, check unconscious soldiers a.s.a.p.!
Note that aliens will not fire on unconscious soldiers. However, any unconscious soldiers caught in a subsequent explosion are always killed, if the blast strength was sufficient to cause ground items to disappear.
While the stun bomb is a significantly safer method of capturing aliens then the Stun Rod, it can only fire one shot between reloads, reducing it's effectiveness over other weapons.
The stun bomb detonates with a radious of 5 tiles, or a diameter of 11 tiles (see graphic).
Likelihood Of Being Stunned
X-COM soldiers in Power Suits (PSs) or Flying Suits (FSs) are unlikely to be knocked unconscious because their armor blocks most of the stun Damage:
- 180 stun double damage maximum * 80% PS/FS stun resistance = 144 max stun damage after resistance,
- Minus 70 (FS Under) to 60 (PS Under) Armor
- Equals 74-84 stun damage at most
- Soldiers have Health from 25 to 61
Experienced soldiers (Health >34) in a Flying Suit are very unlikely to go down, and in fact will usually have no stun damage at all. 144 is the max possible, but the average hit will be 72, which will barely breach FS armor.
Stun Bombs go through Under Armor at ground zero, just as explosives do. Therefore, for a direct hit this is the only number needed.
- Coveralls (Under Armor 2), no resist, 180 max stun damage: Max stun 178, average stun 89. 86% of the time, soldier with lowest Health (25) will be stunned (1-(25/178)). Max excess stun points can be up to 153 (178-25), so you may need up to 16 stimulants to recover!
- Personal Armor (Under Armor 30), 90% stun resist, 162 max stun damage: Max stun 132, average stun 66. 81% of the time, soldier with lowest Health (25) will be stunned (1-(25/132)). Up to 107 excess stun points possible (132-25).
- Power Suit (Under Armor 60), 80% stun resist, 144 max stun damage: Max stun 84, average stun -18 (no stun damage). 41% of the time, soldier with lowest Health (25) will be stunned (1-((60+25)/144)). Up to 59 excess stun points possible (84-25).
- Flying Suit (Under Armor 70), 80% stun resist, 144 max stun damage: Max stun 74, average stun -33 (no stun damage). 34% of the time, soldier with lowest Health (25) will be stunned (1-((70+25)/144)). Up to 49 excess stun points possible (74-25).
The following lists how many times a soldier can fire the gun by shot type continuously in any given round and the remaining percentage of any left over TUs that cannot be spent as a shot.
- Aimed: 1 Shot, 25% Remaining TUs
- Snap: 1 Shot, 35% Remaining TUs
- Auto: Not Available
Stun bomb hits count toward Firing Accuracy skill point increase. If you hit many aliens with one stun bomb, you can get many experience points with the one shot. It still counts towards experience if aliens are caught in its blast, even on the rare occasions that they do not get any stun damage (because their armor blocked it). See blast pattern (above).
The Small Launcher can also provide points to Reactions skill point increase, if fired as an opportunity shot. However, you only get one experience point per shot, even if multiple aliens are caught in the blast. (Technically, you were only reacting to one particular alien.)
Large Units vs. Stun Bombs
Large units, when stunned, stay down for good and are considered dead for the purposes of the battle. There are a few rare exceptions where a portion of the large unit stays awake, but this is not a normal occurance or may only occur on certain ports of the game, such as the Amiga port of UFO.
X-Com controlled tanks, for some reason, never take on stun damage from stun bombs, and are thus the only units in the game that appear to be immune to them.
Sectopods, Cyberdiscs and Reapers on the other hand are vulnerable to stun bomb explosions, particularly on easier levels where their lower armour increases the potency of the stun bombs allowing them to be knocked out by simply standing near the fringe of the explosion. On easier levels, the stun bomb can be treated as a large terror unit buster that also leaves buildings standing afterwards.
On the hardest difficulty level, Superhuman, sectopods require direct hits and have a fair chance of completely shrugging off the damage. This means that you no longer have the ability to wipe out multiple sectoods with a single stun bomb. Cyberdiscs and Reapers can still be dealt with stun bombs.
In short, the ease of knocking out a large unit completely varies depending on your difficulty level.
Note: Cyberdiscs knocked out with a stun bomb do not always cause an explosion, but it's best to be beyond their blast radius as a precaution.
Stun Bombs vs. HE Block
Walls and some objects usually have a parameter called HE Block (HEB) set. This stops the progress of explosions (and makes walls walls). HE Block also stops the effect of a stun bomb blast, just as it does for "regular" (HE) explosions. However, it does lead to some odd results...
Typically, HE explosions do damage to units in a range of 50%-150% of the explosion strength as of the tile in question. However, the stun bomb does not follow the usual rule for imparting damage; instead it imparts 0-200% of its stun "explosion" strength to units, as of the tile in question, even though it's damage drops off by 10 per tile, as with other explosions. Thus it uses a hybrid of explosion and firearm damage mechanics.
This leads to an "odd" scenario like this, as seen in limited testing:
- If a stun bomb is hacked to strength 250 stun and shot at a wall with HE Block of 120, no units behind it receive any stun. This follows the usual "ground" rules of: Half strength is applied to terrain at ground zero (GZ), which falls off by 5 per tile away from GZ; thus the stun bomb is 125 vs. terrain at GZ and 120 at GZ+1. Soldiers got no stun because the 120 HE Block nullified it. (Wall armor was set to 0 - tile armor never impedes explosions; only HEB does.)
- If the 250 stun bomb is shot at a wall with 110 HEB, a unit right on the far side was seen to get 33 damage. How did that work? Another rules hybrid:
- The stun bomb is 125 vs. terrain at GZ
- At GZ+1, it is 120, minus the 110 HEB, leaves 10 for damage to terrain
- But damage to terrain is 50% of the average explosion damage. And the stun bomb can do up to 200% damage to units. If 10 is 50%, then 40 is 200%. Thus, it "makes sense" that a unit was hit for 33. In its own weird way.