VATS

The Vault-Tec Assisted Targeting System, or V.A.T.S.is a queuing system for Fallout 3, inspired partly by the ability to target specific body parts in the turn-based combat system of Fallout and Fallout 2.

While using V.A.T.S., the otherwise real-time combat is paused. Various actions cost action points, and both the player and enemies can target specific body areas for attacks, inflicting specific injuries.

When using V.A.T.S. against a humanoid enemy, there are generally seven different areas that are targetable; the head, torso, left arm, right arm, currently held weapon, left leg, and right leg. However, there may be other points available when specifically facing off non-humanoid creatures (I.E. Bloatfly wings, Ant's Antenna). When targeting a part, the screen displays a percentage of how likely the attack will hit the targeted area based on distance from the target, and combat skill. Unlike previous Fallout games, it is not possible to target the eyes or groin nor target any individual body parts in melee and unarmed combat, however there is a seemingly random chance to decapitate and slice off the limbs of the enemy even though you cannot aim for specific parts.

It is also possible to target a thrown grenade before it reaches you, or even to shoot the grenade while it's still in the target's hand (to devastating effect).

VATS is introduced to the player character on their 10th birthday in the vault upon receiving a BB gun.