This new puzzle game has been making the rounds.  If you're into engineering, programming or puzzle games in general, you should give it a look.  It's not for everyone, and it's a little confusing at first, but I'm really enjoying it.  It's chemistry-themed, but the puzzles themselves don't require any chemistry knowledge.  It's more about programming.  It also shows you how efficient your solution was compared to other users, and it can automatically upload videos of your solutions to Youtube.  There's a demo, and it works on Windows, Mac and Linux.

http://www.spacechemthegame.com/