You're a tiny triangle trapped inside an imploding hexagon. Bits of hex are rushing inwards to crush you so you have to scoot around the edges of a hexagonal core to survive their assault. The bloopy tones of Chipzel helps to poke your grey matter into a frenzied sort of urgency as the bastard hexagon rotates and changes colour, threatening to crush you in a cold, hexy embrace.
Super Hexagon is the latest game from Terry Cavanagh, who made the awesome platformer VVVVVV . It's out on iPhone and iPad now, but he mentions that "PC and Mac versions are coming later" in the description for the launch trailer, which you'll find embedded below. Be warned, it might make your brain go a bit funny.