http://www.ganggarrison.com/ Check it out its a 2D game based on Team fortress. Gang Garrison 2 presents the player with 9 unique classes to use in frenetic, cooperative multiplayer action in a stylish and unique 8-bit style. Battle with your friends or others you encounter online through a whole range of vibrant maps; TF2 maps reimagined in 2D as well as a multitude of maps with all sorts of different looks and settings, all of which have been dreamed up and constructed by members of our community. We've made a huge effort to provide simple, bugfree custom map support, so that anyone with a paint application can put together a map and test it themselves with our Garrison Builder utility. We also gladly encourage Gang Garrison modifications; many successful mods have been incorporated into the game as new features.

Tried it.

its OK but needs in-game chat and a little better graphics.