Grand Theft Auto IV is an action-adventure game played from a third-person perspective.[2] Players complete missions—linear scenarios with set objectives—to progress through the story. It is possible to have several active missions running at one time, as some require players to wait for further instructions or events. Outside of missions, players can freely roam the game's open world and complete optional side missions.[3] Composed of the fictional city of Liberty City, the world is larger in area than most earlier Grand Theft Auto series entries.[4] At the beginning of the game, players can only explore a limited area—Bohan, Broker, and Dukes—with all other islands unlocking as the story progresses.[5]
Players use melee attacks, firearms and explosives to fight enemies, and may run, jump, swim or use vehicles to navigate the game's world. There is a first-person perspective option when using vehicles. In combat, auto-aim and a cover system can be used as assistance against enemies. Should players take damage, their health meter can regenerate by consuming food or drinks, using medical kits, or calling for paramedics.[6] If players commit crimes, law enforcement may respond as indicated by a "wanted" meter in the head-up display (HUD). On the meter, a count of stars indicates the current wanted level. Gaining more stars will cause law enforcement to incapacitate players more aggressively and extends the wanted vicinity area, and is capped at six stars. The player can evade police by travelling outside the wanted vicinity area, after this the wanted meter enters a cool-down mode, law enforcement hunt for the player, and eventually recedes when they are hidden from the officers' line of sight.[7]