|Protector is a defender clone. You fly a single ship against a suspiciously familiar Evil Empire. Bugs, lawyers, bundles, red tape and even more evil creatures will try to stop you.|
Protector is free, which is pretty good value for money. It works on DOS, Windows 9x, and Linux.
Click here to download the game(DOS/windows version, 484K), or here to download the source code(113K)
Here's a screenshot.
Two people can play at once!