Adventure Games
A number of adventure games support up to four players. Games such as "Champions of Norath" or "X-Men Legends II: Rise of Apocalypse" allow up to four players to join together and play cooperatively. Players work their way through levels destroying enemies and occasionally solving puzzles. These games often get easier with each additional player, however some games feature scaling where the number and difficulty of enemies adjusts for each added player.
Shooters
Many first- and third-person shooters support the multi-tap. "Timesplitters" and "Unreal Tournament" are popular franchises that both have PS2 iterations. These games split the screens into boxes to support up to four players as they attempt to destroy each other. Some unconventional shooters such as "Twisted Metal: Black," where players drive cars equipped with weapons, also feature four-player support.
Music Games
A fairly recent phenomenon in gaming is the advent of music games. These games allow players to form a band and take turns playing controllers shaped like instruments. Microphones, guitars and drums are all available, and the game will mark your progress as you progress from a garage rock outift to full-fledged rock stars. Rock Band and Guitar Hero are two of the most popular games of this type.
Sports Games
By far the most common game genre to feature four-player support is sports games. A large number of games including basketball games such as "NBA Street Vol 2.," baseball games such as "MVP 06," car racing games such as "Nascar Thunder 2004" and several others all feature competitive and co-operative four-player support. You can play through a season with a group of friends or set up tournaments to see who is the best.