Grand Theft Auto 4 has 16-player multiplayer with 15 different modes (including co-op missions)

Grand Theft Auto 4 car chase screenshot
The latest issue of the Spanish PlayStation magazine reports on Grand Theft Auto 4, it shows new screenshots, as well as the first details on Grand Theft Auto 4’s multiplayer system.

There are 15 multiplayer game modes in GTA 4. Multiplayer supports upto 16 players. PSM had an opportunity to play 7 of them and said the rules of each game are determined by the host. Your online character is fully customizable. You can alter his race, sex, hair, clothing, etc.

Here are the full details on GTA 4’s multiplayer system. But first, the game modes featured are as follows:
Pre-order Grand Theft Auto 4 for Xbox 3601. Hangman’s Noose
2. Car Jack City
3. Bomb da Base
4. Bomb da Base II
5. Mafia Work
6. Team Mafia Work
7. Deathmatch
8. Team Deathmatch
9. Turf War
10. Cops n Crooks
11. Race
12. GTA Race
13. Deal Breaker
14. Free Mode
15. (some other mode?)

* In Race and GTA Race, the host gets to decide which vehicles are involved, and the number of laps to be played. You can shoot and throw molotovs from the window, and even steal your rivals’ car.
* In Deathmatch and Team Deathmatch, the host gets to decide whether the police can intervene or not. The host also gets to decide the number of pedestrians, the amount of traffic, and the type of weapons.
* In Cops n Crooks, one team play as cops and the other play as criminals. The cops must stop the criminals from escaping. They can monitor the locations of the criminals on their GPS systems, while the criminals have no idea where the cops are.
* In Mafia Work and Team Mafia Work, you play as one of Kenny Petrovic’s mafia henchmen. You must complete hits ordered by the boss (via the cellphone) before your rivals are able to do so.
* A single-player mission called “Hangman’s Noose” features co-op. You and your friends will be able to escort a mobster, while being pursused by a SWAT team.
* The map used in multiplayer is the same map that is used for single player. — Via