Web Wars is an open source arena shooter similar to Geometry Wars, Robotron, or Death vs Monstars. It has 12 stages, 3 difficulty levels, 9 enemy types, and weapon upgrades.
New version: more particles and other special effects, better installer. Verified to work on Windows, Linux, Mac. Click on the jar to install. Choose a directory to install it. Click on the WebWars jar in the install directory to start the game.