A few friends and I have been working on a game for quite a while. We're finally done! FattyWars is a multiplayer space shooter. Designed for playing with unlimited* friends, and you can also play against the computer. Works best with dual analog controllers, but keyboard/mouse works too.
You can download it from the FattyWars page. Works in Windows, Mac, and Linux.
* seriously. As many controllers as your computer can handle