A critical hit is a gameplay mechanic in XCOM: Enemy Unknown.
Overview
When firing most weapons, units have a chance to inflict additional damage (+50%, rounded down to the nearest whole number) upon their opponent with a critical hit. A unit's Critical Hit Damage and Critical Hit Chance stats are partially composed of base stats added by the weapon being used, but may vary from encounter to encounter due to many factors established by both the shooter and the intended victim. These include both party's pertinent traits, abilities, status effects, gene mods, equipment & upgrades, as well as the positioning of the units. Catching a target out of cover (referred to as "Enemy Exposed" in-game), or flanking from an unprotected side, increases the chance of a critical hit by +50%.
Hit Chance
The critical percent displayed in-game indicates the chance of a successful hit being critical, not the chance of landing a critical hit against the opponent. To determine the latter, multiply the displayed chance to hit by the critical percentage. For example, if you have a 88% chance to hit the target, and a 25% critical chance, the percent outcomes are:
- Chance to hit (with critical damage): 88% × .25 = 22%
- Chance to hit (with regular damage): 88% - 22% = 66%
- Chance to miss: 100% - 22% - 66% = 12%
Also note that while Aim and Defense modify the chance of a hit, they are not directly related to Critical Hit Chance or Critical Hit Damage stats.
Weapons
Most weapons, excluding rocket launchers and grenades, are capable of inflicting a critical hit. Of all the primary weapon types, sniper rifles have the highest base chance to inflict a critical hit throughout the game, increasing by +5% critical chance with each technology level. Heavy's LMGs have the lowest critical chance, remaining at zero from conventional weapon through to plasma. The Laser Pistol is the only secondary weapon that has a base chance to critically hit.
| Weapon | Base Damage | Critical Chance | Critical Damage |
|---|---|---|---|
| Light Machine Guns | |||
 LMG
|
3 - 5 | 0% | 6 - 8 |
 Heavy Laser
|
5 - 7 | 0% | 9 - 11 |
 Heavy Plasma
|
8 - 10 | 0% | 14 - 16 |
| MEC | |||
 Minigun
|
4 - 6 | 10% | 8 - 10 |
 Railgun
|
6 - 8 | 10% | 11 - 13 |
 Particle Cannon
|
9 - 11 | 10% | 15 - 17 |
| Pistols | |||
 Pistol
|
1 - 2 | 0% | 2 - 4 |
 Laser Pistol
|
1 - 3 | 10% | 3 - 5 |
 Plasma Pistol
|
2 - 4 | 0% | 5 - 7 |
| Rifles | |||
 Assault Rifle
|
2 - 4 | 10% | 5 - 7 |
 Laser Rifle
|
4 - 6 | 10% | 8 - 10 |
 Light Plasma Rifle
|
4 - 6 | 10% | 8 - 10 |
 Plasma Rifle
|
6 - 8 | 10% | 11 - 13 |
| Shotguns | |||
 Shotgun
|
3 - 5 | 20% | 6 - 8 |
 Scatter Laser
|
5 - 7 | 20% | 9 - 11 |
 Alloy Cannon
|
8 - 10 | 20% | 14 - 16 |
| Sniper Rifles | |||
 Sniper Rifle
|
3 - 5 | 25% | 6 - 8 |
 Laser Sniper Rifle
|
5 - 7 | 30% | 9 - 11 |
 Plasma Sniper Rifle
|
8 - 10 | 35% | 14 - 16 |
Bonuses and Perks
Beyond weapons and troop positioning, there are a substantial number of ways to increase one's chance of avoiding a critical hit, inflicting a critical hit, and critical hit damage.
Basic Abilities and Traits
| Ability / Trait | Description |
|---|---|
 Hardened
|
-60% critical chance against this unit. XCOM: MEC Trooper, all varieties of S.H.I.V.s Enemies: Berserker, Chryssalid, Cyberdisc (closed), Drone, Ethereal, Mechtoid, Sectopod, Uber Ethereal |
 Hunker Down
|
Immune to being critically hit (unless flanked). XCOM: Assault, Heavy, Sniper, Support Enemies: All EXALT units, most Alien land units |
 Overwatch
|
Reaction shots on Overwatch cannot critically hit. XCOM: All units Enemies: All EXALT units, Cyberdisc, Floater, Heavy Floater, Mechtoid, Muton, Muton Elite, Outsider, Sectoid, Sectoid Commander, Sectopod, Thin Man |
Note: Although they have a similar name and purpose, the civilian ability Head Down is not the same as Hunker Down. Head Down does not provide immunity to critical hits.
Class Abilities
| Class | Ability | Description |
|---|---|---|
 Assault |
 Aggression
|
+10% critical chance per enemy in sight (max +30%). |
 Bring Em On
|
+1 critical damage per enemy the squad can see (max +5). | |
 Close and Personal
|
+30% critical chance against adjacent targets. (Doesn't apply in XCOM: Enemy Within due to change to ability.) | |
 Killer Instinct
|
Run & Gun grants +50% critical damage. | |
 Resilience
|
Immune to being critically hit. | |
 MEC EW |
 Body Shield
|
The nearest visible enemy cannot critically hit this unit. (Heavy-based MEC Troopers) |
 Collateral Damage
|
Collateral Damage cannot critically hit. | |
 Platform Stability
|
+10% critical chance. (Sniper-based MEC Troopers) | |
 Sniper |
 Disabling Shot
|
Disabling Shot cannot critically hit. |
 Headshot
|
+30% critical chance, and +critical damage based on the tech level of the rifle. | |
 Opportunist
|
Allows reaction shots (e.g. Overwatch) to critically hit. | |
 Squadsight
|
XCOM: Enemy Within only: Squadsight shots cannot critically hit, unless a Headshot. | |
 Support |
 Combat Drugs
|
Smoke Grenades grant +10% critical chance for all units in the cloud. |
The Heavy class is the only soldier class that does not have a class ability involving critical hits. The only critical hit perks available to Heavies are ones available to all (non-MEC) classes, such as Reaper Rounds and Gene Mods. A Heavy that becomes a MEC Trooper gets a critical hit defense ability, Body Shield.
Equipment Abilities
| Ability | Description |
|---|---|
 Ghost Mode
|
+100% critical chance while stealthed (+30% in XCOM: Enemy Within). XCOM: soldier with Ghost Armor / Ghost Grenade EW Enemies: None (ability possessed by Seekers but cannot be used to crit) |
 Reaper Rounds EW
|
+20% critical chance against organic targets. XCOM: Soldier with conventional weapon & Reaper Rounds Enemies: None |
Gene Mods
| Gene Mod | Description |
|---|---|
 Adrenal Neurosympathy EW
|
+5% critical chance. XCOM: Gene-modded soldier & nearby allies Enemies: None |
 Adrenaline Surge EW
|
+10% critical chance per turn when wounded. XCOM: None Enemies: EXALT Elite Operative |
 Depth Perception EW
|
+5% critical chance bonus for height advantage. XCOM: Gene-modded soldier] Enemies: EXALT Elite Sniper |
 Mimetic Skin EW
|
+30% critical chance when stealthed. XCOM: Gene-modded soldier Enemies: None |
Foundry Upgrades
| Upgrade | Description |
|---|---|
 Improved Pistol I
|
+20% critical chance with all pistols. |
 S.C.O.P.E. Upgrade
|
+10% critical chance added to the S.C.O.P.E. |
Miscellaneous
| Ability | Description |
|---|---|
 Council Medal of Honor EW
|
+10% critical chance if not within 7 tiles of an allied unit. XCOM: Soldier Enemies: None |
 Greater Mind Merge
|
Receiver is granted +25% critical chance. XCOM: None Enemies: Sectoid Commander (transmitter), Sectoid (receiver) |
 Mind Merge
|
Receiver is granted +25% critical chance. XCOM: None Enemies: Sectoid (transmitter/receiver) |
Absolutely Critical
Absolutely Critical is a Second Wave option available only after finishing the game on Normal difficulty. It makes a substantial change by increasing the "Enemy Exposed" and "Flanking" bonuses from +50% to +100% critical chance, while modifying the Hardened trait from -60% to -100% critical chance to compensate for units that cannot take cover. While this option makes flanking or being out of cover more dangerous, it also means that there is a net 10% increase to critically hit a Hardened unit.