Team Fortress 2

Team Fortress 2 (A.K.A TF2) is a first-person shooter that is nearly exclusively a mulitplayer game, and one of the few FPS games where the dominant game mode isn't deathmatch. Players join a team and work together to capture intel and bring it back to their base, control territories or just kill each other. Each player can choose from nine classes, all with their different strengths and weaknesses of course, which are Scout, Soldier, Pyro, Demoman, Heavy, Engineer, Medic, Sniper and Spy. The game is well known for its hats. These are customization items, generally wore on the characters' head (although the official TF2 blog describes a pin as being a hat