Quite probably the hardest game you'll ever play
Super Hexagon is an insanely difficult, abstract twitch game where players have to navigate through a maze that's continually collapsing in on a central shape. The pulsing rhythm and constant spinning of the play area make this really, really hard, plus the fast-paced soundtrack isn't likely to calm your nerves at any rate.
There are three difficulties to start, and as you beat each stage, a new version of the level unlocks that has the same track go at what feels like twice the regular speed. It gets a little ridiculous. This is an absolutely fantastic game - so long as you're a glutton for punishment.