Fallout: New Vegas VATS

V.A.T.S. or the Vault-Tec Assisted Targeting System is a statistic-based combat system

Background
The mechanic allows the player to freeze combat and target specific limbs, utilizing Action Points.

Effects

 * Every melee weapon can execute a special attack, that requires Melee Weapons skill of at least 50.
 * Unarmed weapons gain Uppercut and Stomp special attacks at skill level 50, and Cross at skill level 75. These attacks have an AP cost of 20 regardless of the weapon used.
 * Base melee/unarmed damage (except thrown melee weapons) dealt by the weapon is automatically doubled.
 * The player character takes 75% damage in V.A.T.S. instead of 10%.
 * The V.A.T.S. critical chance bonus is 5% instead of 15%.
 * V.A.T.S. does not inflict additional weapon's durability damage on use.

Bugs

 * V.A.T.S. targeting is bugged for certain guns - most lever-action rifles and a few pistols: it consistently shoots high, making headshots improbable or impossible. Consistently replicable by starting a new game, adding a brush gun (id: 00121148) and .45-70 ammo (id: 0013e43e), forcing Guns to 100, and shooting at Easy Pete's head from the nearby road. Bullet impacts will appear on the windowpane behind him - and, shot after shot, will consistently be high. Modifying the gun to have perfect accuracy and/or setting fVATSSpreadMult to 0.01 will reveal that the V.A.T.S. point of aim is roughly a foot high. No known fix yet. This bug also seems to occur with the Hunting Revolver.
 * While attacking in V.A.T.S., only the target and player will be in slow motion. Any other enemies in the area will move and attack at normal speed.
 * Sometimes the camera may zoom on the enemy and all your shots may fire in quick succession as if you're using an automatic weapon, but no shots will register on the target and will cause zero damage.