Tetrobot is easily one of the best puzzle games I've played in the past few years. It's well crafted, the difficulty curve is just right and you'll get some pretty good headscratchers on the road to 100%. Another thing that I liked is that your bot doesn't gain abilities during the adventure. What I mean is that, although new mechanics are regularly introduced, when your enter a level you know you already have all the tools to get all the collectibles. There's no "come back later when you've gain ability X". Even if it seems impossible to get that last piece, the solution is always within reach, you just have to think harder :)
