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, explosion graphics and firing sound 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, they will continue to lose health while unconscious, and can even die. So if there is any question in your mind, check unconscious soldiers ASAP!
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 than the Stun Rod, it can only fire one shot between reloads, reducing its effectiveness over other weapons.
The stun bomb detonates with a radius 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 88. 85% of the time, soldier with lowest Health (25) will be stunned (1-((25+2)/180)). Max excess stun points can be up to 153 (178-25), so you may need up to 39 stimulants to recover!
- Personal Armor (Under Armor 30), 90% stun resist, 162 max stun damage: Max stun 132, average stun 51. 76% of the time, soldier with lowest Health (25) will be stunned (1-((25+30)/162)). Up to 107 excess stun points possible (132-25), requiring up to 27 stimulants.
- Power Suit (Under Armor 60), 80% stun resist, 144 max stun damage: Max stun 84, average stun 12. 41% of the time, soldier with lowest Health (25) will be stunned (1-((25+60)/144)). Up to 59 excess stun points possible (84-25), requiring up to 15 stimulants.
- Flying Suit (Under Armor 70), 80% stun resist, 144 max stun damage: Max stun 74, average stun 2. 34% of the time, soldier with lowest Health (25) will be stunned (1-((25+70)/144)). Up to 49 excess stun points possible (74-25), requiring up to 13 stimulants.
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, 60% Remaining TUs (Soldiers with 67, 69 or 71+ TU can reload and fire a second shot, if they do nothing else.)
- 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 versus 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 never take on stun damage, and together with Zombies are the only units in the game that are 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 sectopods 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 versus terrain and objects
Stun Bombs do not damage the terrain at hand or destroy objects on the ground. As such, they are safe to use near UFO Power Sources, as there is no risk of damaging the precious Elerium (probably that's why alien Engineers use these).
Stun bomb explosions
Stun bomb explosions have the radius seen in the picture above, and follow explosion rules such as that they are 90 average stun at center, which drops off by 10 damage per tile away from ground zero. Ok. But unlike most explosives, their damage to units is 0-200% of the rated stun damage at any given point. (Explosives usually inflict 50-150% of damage to units, at any given point.) Thus they are unique in the game in that they spread like explosives, but damage like shot weapons. For more details, see Explosions#Stun_Bombs.