GTA IV will support sixteen players simultaneously on both Xbox Live and PlayStation Network and many of the twelve included game modes are playable individually or as part of a team. The modes are: Deathmatch, Mafia Work, Race, GTA Race, Cops 'n' Crooks, Hangman's Noose, Deal Breaker, Turf War, Car Jack City, Bomb Da Base I, Bomb Da Base II, Free Roam
* The game host determines the rules of the game prior to it starting, with options for weapons, number of pedestrians, traffic level and police intervention being some of many available.
* Players can choose a variety of customizable characters before the game begins on a map which is said to be the same as the single player version.
* In the race modes, the host can determine how many laps to undertake and players can shoot and throw grenades from the car. GTA Race is a similar mode, with the added twist that players have the ability to steal opponents cars.
* Cops 'n' Crooks splits players into two teams - the cops and the crooks. Cops can see the location of the crooks on the radar and must hunt them down. Crooks don't have the luxury of knowing their rivals' location.
* The Mafia Work modes involve assassinations, with one player being earmarked as the target and the rest of the players in the game racing to kill them first.
* Hangman's Noose provides a link between the single and multiplayer modes by allowing players to undertake a cooperative mission from the single player mode where a mobster must be escorted and kept alive against the attacks from the pursuing police.