Super Hexagon is fantastic. Extremely difficult but never impossible, the game has clearly been tuned very finely. And it's totally addictive. You *WILL* be frustrated, curse Terry Cavanagh's name, and ragequit. And then five minutes later you'll find yourself playing it again. I've put maybe 50 hours into this very cheap game, so it's great value too. Also, the soundtrack is awesome. Highly recommended.