I came across this game by accident while cruising around YouTube with my Son. I have been a huge fan of Terry Cavanagh for many years, so of course I was familiar with Super Hexagon.
Open Hexagon is unique in that, it is not just a clone of Super Hexagon, though make no mistake, it is a clone at heart, it also leaves the door open for user generated content. And thus, unlike its original parent game, it has many many expansions available with good music and creative levels for users to enjoy.
After going back to the original Super Hexagon, I find that this clone version has a lot less visual
interference and is thus easier to play. But that's just my opinion.
Download Open Hexagon from the developers site here