http://www.spacechemthegame.com/
Surely a bit less difficult than Robot Odyssey, but immensely enjoyable nonetheless. I finally forced myself to uninstall it after spending waaaay too much time hyperoptimizing my solutions against the online leaderboard... it was rather addicting. :)
Incidentally, I didn't realize that he was the creator of Infiniminer. For those unfamiliar with the game, it is what inspired Notch to create Minecraft.
I'm glad this guy went into game-making.
On another note, the histograms you get after beating a level are the best high score screen implementation I have ever seen. I gush over them whenever I get the chance.
I have (or had, I guess) the same sort of response to the score screens at the end of a Firefight game in Halo ODST. It would show you charts and tables for your progress through waves, your weapon usage and kills per enemy, a graph of your deaths, etc. Every game should provide stats like that.