Terry Cavanagh's Super Hexagon is challenging enough without throwing depth and lateral movement into the mix, but that's what Kevin Messman has done with Rotational. Described by its creator as a "love letter to Hexagon," Rotational involves similar slip-through-the-shapes gameplay while shifting the action to the surface of a sphere.
Like Super Hexagon, the music is retro and the visuals are sparse; also like Super Hexagon, you're unlikely to last more than a few seconds before succumbing to the onslaught of geometry. It's a free download for both Mac and PC.