The new modes, all described in detail after the jump, include Team Mafiaya Work, Team Car Jack City, Turf War and Race.
Newly Detailed Modes
Team Mafiaya Work: (2 to 8 teams) You're a member of a crew doing contract work for the mafiya—including such plum gigs as escorting wanted men, picking up MacGuffins and stealing cars. Work as a team to complete contracts before the time period ends and get the rewards. You'll probably want to do your best to scupper the other crew's work as well. Each contract you complete gives your team cash, and the crew with the most cash at the end of the round wins.
Team Car Jack City: (2 - 8 teams) Cars spawn parked around the map and the teams must steal then and take them to a drop off point. Teh cash teams get for dropping of stolen vehicles depends on their condition—teams get less cash the more damaged they are. The exception to this are special bonus cars, stuffed with drugs, which five a set amount of cash on delivery no matter how damaged they are. Your crew has to get hold of whatever vehicles the boss wants. Whichever crew makes the most money wins. Simple.
Turf War: (2 teams only) A timed capture-the-base mode. There are a number of bases around the map that you have to take by stand on on them for a short period of time. The more players that are on a base, the faster it can be captures. The more bases that your team owns, the faster your team's cash score increases. If the rival gang is on or near a base, you won't be be able to take control of it—so do what you can to try and... displace them. The team with the most cash at the end of the round wins.
Race: Race to the finish through each checkpoint in order. If you take a wrong turn or mess up in some way, you can respawn your vehicle on the last checkpoint you passed. There is a large selection of races for cars, boats , and helicopters—you can choose laps and vehicle class/type. This mode has two sub-modes: Free Race and Cannonball Run.
Free race are point-to-point races. First one to reach the end point inws.
Cannonball Run are races where you have to reaverse several checkpoints any way you can.
Modes we knew about
GTA Race: Rockstar North's twist on the concept of a race. Host selects vehicle type (each racer selects his or her specific vehicle after that), race, number of laps, and time limit. Despite ordered checkpoints, players can go anywhere in the city at any time. Do you want a straightforward race from start to finish or do you want to create a roadblock and shoot rockets at your fellow racers? The choice is yours - each player does it slightly differently. 16 players max.
Cops N Crooks: 2 teams, 2 vastly different goals. The cops can see the crooks on their radar but the the crooks can only see the escape point making this the ultimate cat and mouse situation. For the first time, players can get a chance to be on the other side of the law in a Grand Theft Auto with Cops n' Crooks. A team of "crooks" need to get their boss to safety, as the team of "cops" pulls out every trick in the book to try and stop this from happening. Again, 16 players max.
Hangman's NOOSE: Co-op in Grand theft Auto IV is a 4 person affair. Each mode is a short, story-based mission you must complete with your friends. In Hangman's NOOSE you must get crime boss to an extraction point alive. First, several of Liberty City's finest need to be dealt with and then transport must be secured. Will you take Kenny to safety in an armoured car? How about a motorcycle or attack chopper? The choice is all yours.
Team Deathmatch: Classic deathmatch done Grand Theft Auto style. Go anywhere, do anything: the whole city is yours. 16 players max, teams can be made in any configuration. Weapons on the ground can be configured by the host. Capitalism rules here: the team with the most money in the end is the winner.