Hi,
My friends and I have been working on a game for the last month. It's called Ultimate Zombie Fighters (uzf). It is an open source, cross-platform, 2d top-down zombie shooting game inspired by Call of Duty 5: Nazi Zombies.
We just released a 0.1 version which is kinda playable. You can get it from it's website: http://uzf.sf.net
Screenshot:
There are executables for windows available, but for linux(tested) and mac(not tested) you will need to compile.
To compile from source you need:
cmake
SFML >= 1.5
Box2D >= 2.1 (I think)
Please try it out and let us know what you think.
Thanks!