Team Fortress 2 is the latest incarnation in the venerable Team Fortress line of games, starting with the very first mod for Quake. If you are a veteran, you can skip the rest of this paragraph. Team Fortress is based around two opposing teams, Red and Blue; these teams are made up of various classes with different abilities. For example, the Pyro's primary weapon is a flamethrower, the Medic heals other players, the Demoman is equipped with various explosives, et cetera.
Team Fortress 2 takes the formula we all know and love and updates it, giving us a great new game. One thing should be said up front: this is not Team Fortress Classic. Capture the flag is now a minor gameplay mode, only present on one of the included maps. The classes have been revamped; their roles are familiar, but the way they play is new. The game also has a striking new visual style, a cartoony 60's spy movie theme that is filled with character and atmosphere.
I heartily reccomend Team Fortress 2 for all Team Fortress veterans, and for anyone who enjoys a great multiplayer shooter. It bucks the recent trend of realistic gameplay and gives you something else: pure, undiluted fun. The amount of chaos and mayhem in a Team Fortress 2 match is beyond description, and it is the sort of game that easily sucks you in for hours and leaves you smiling. The game as-is has some minor flaws, such as imperfect balance for some of the classes, but there have already been a series of patches adjusting these, and more will certainly be on the way. The flaws are minor, and do not detract from the game.