And... I'm done! Cavernous Shooter! is a top-down shooter set in a cave environment. Try to fight your way through the entire cave system.

Controls:
[WASD] or [Arrows] to move
[Left mouse] to shoot
[Right mouse] to fire shotgun (if you have ammo for it)
[R] to reload
[Q] to toggle particle quality settings

The linked zip file contains .bat and .exe files for Windows, or .sh for Linux and OSX. It also contains the game source code.

There is also a web (Java Webstart) link - just run the .jnlp through your java/bin/javaws.exe (most browsers will default to this behaviour).