A system to let the player cover from gun fire is a feature that has debuted with the introducing of over-the-shoulder view in Grand Theft Auto III and has been immensely expanded in Grand Theft Auto IV. Games that uses the bird's eye view has very little form of cover, mainly only running behind objects to hide from gun fire.
GTA III — GTA Vice City Stories
In GTA III, in order to cover from gun fire, the player is limited to running behind cars and structure. With the introduction of crouching in GTA Vice City, the player can run behind shorter structures that are otherwise pointless in GTA III so the player's body is less exposed to gun fire. This is especially advantageous on the PC version where the bullets travel to the crosshair and not obstructed by barriers usually experienced using the console or classic controls. Powerful weapons that can only be targeted in first-person view in the console or classic controls are extremely useful in the PC version being able to target in third person view. GTA San Andreas added the additional ability to travel while crouching and rolling over sideways while crouching.
Grand Theft Auto IV dramatically expanded this idea into a system with a simple press of a button. The cover button can let the player automatically find a nearby object to hide behind. The character great number of animations are available just to approach the cover, including running into cover, rolling into cover, sliding into cover, and going from cover to cover.
Once behind cover, the player can strafe left or right if there is room, hugging close to the cover. At the edge of a cover, the player can blind fire without exposing the major parts of the body to receive minimal damage. A major disadvantage to this is that accuracy is dramatically reduced. The new system allows the player to throw projectiles and explosives without damaging oneself in the process. The player can shoot out of cover instead and after the player stops shooting, the character will automatically hide behind cover.