Today, I committed the initial release of SpaceZombies, a top-down space shooter, to Github. SpaceZombies features my brand new particle engine, which includes dynamically colored particles, fading, particle emitters, randomized particle spreading, and removal of particles after a fixed amount of time.
If you wish to download SpaceZombies in an executable jar file, you can find it at http://www.0rleans.com/projectDownloads/spaceZombies/?p=download.
The source for SpaceZombies can be found at https://github.com/dudeofawesome/JavaZombies.