Ok, a week ago, I started a challenge to make a game in a week.
Now, a week older, a little more sleep deprived, I present my entry in the challenge:
Should work on Linux, Mac, or Windows PC. Heck, it might work on your SGI or Amiga, if you try hard enough.
I'm proud to have got something done, and there are still a bunch of features I'd like to add into the game (beefed up level editor, storing and playing back trajectories, more levels, online matchmaking). Maybe I'll expand it into a commercial product. It's playable. I'm even told it's fun.