I have actually been having a blast with the 16 player online multiplayer for GTA4. The single player is ok but the multiplayer is where its at for GTA4.
16 players thru the entire city including helicopters, boats, bikes, cars, trucks, pedestrians, and cops. You can select individual islands to play on or you can play with every island open if you want. You can turn cops on or off, turn pedestrians on or off, set the amount of pedestrians or traffic on the street or none, put whatever weapons you want, set spawn time and spawn distance, time of day, weather, just about anything along with 15 total multiplayer game modes including some that are 4 player co-op missions. You can even set up online races with boats, cars, trucks, bikes, helicopters, police cars, SWAT trucks, and even firetrucks. lol I have hosted matches with the entire game open and also hosted matches with only shotguns at the prison. Also hosted matches with just rockets on. Lots and lots of options for sure and anywhere you want to play, you can. You can make the game setup as big or small as you want. I have even set up grenade only matches.