OK, ok…if you don't know what this is then I guess you came to the right place. Team Fortress is the most commonly played quake mod in the world. There are a lot of other great ones too, but it has the most different ways to play. You get to pick from one of 9 different guys: Scout, Demoman, HWGuy, Medic, Soldier, Spy, Sniper, Pyro, or Engineer. Each one has his different strengths and weaknesses.

Guy	Strengths and Weaknesses	Special Commands*
Scout	Fast, weak	None
Demoman	Great defensive, average speed	Detpipe
HWGuy	Very Strong, Slow	+det5, +det20, +det50
Soldier	Average speed, strong, has to reload after a few shots	None
Pyro	Sets things on fire that keeps on hurting, average strength	None
Medic	Above average speed, can heal other teammates, this is a very balanced guy	None
Spy	Can make the other team think he is dead or on their team, weak	Feign (look like you're dead), Disguise (change team colors and skin)
Sniper	One hit kills, slow when aiming	None
Engineer	Can build weapons of destruction, vulnerable while building	Build (Let's you build an upgrade-able gun or a weapon station)

*This changes when you are playing Mega TF. There are certain commands that every player has; +gren1, +gren2. Each player has a unique type 2 grenade.

Hey! Get TF now!!!

Team fortress has a whole lot of maps. You will need to find a decent site that will let you download these as well. You can find a lot more information on Team Fortress on their Home Page.