50 Rocks, 50 Guns.
The game is here! More precisely at this link. Please be prepared for a stupid difficulty curve that makes no sense.
W, up arrow: move forwards
A, left arrow: rotate left
D, right arrow: rotate right
Essentially you have a spaceship with which you must save the earth from a giant asteroid, and many high tech and improvised weapons with which to do it. In total, 100 objects take part in the gameplay (excluding the approaching planet in the background). The interesting part is that the number of asteroid chunks is exactly equal to the number you could theoretically destroy. That is, every miss means another tonne of asteroid smashing into the earth. I haven’t actually won it yet.
You may need to download these:
Microsoft Visual C++ 2008 SP1 Redistributable Package (x86)
DirectX End-User Runtime Web Installer
DirectX has updates every few months that don’t change the version number but are still required, eg there are many updated versions of DirectX 9.0c. This uses one from August 2009 iirc.