Update 1 - there's been some kind of breakdown in communications here, as it transpires that Terry Cavanagh isn't as cool with this game as we first thought. While the Open Hexagon dev was given a blessing to make a game 'inspired' by Super Hexagon, he was explicitly told that it couldn't be a clone. And yet... So, if you like Open Hexagon please be sure to give your support to the creator of the game it so liberally borrows from once Super Hexagon itself arrives on PC.
Update 2 - the creator of Open Hexagon has apologised profusely for releasing his clone game before the PC/Mac version of Super Hexagon, and attempted to explain why he got the wrong end of the stick.
Terry "VVVVVV/delightful human being" Cavanagh's Super Hexagon is an evil, evil thing. Other games take the time to introduce themselves and shake your hand. Super Hexagon immediately punches you in the face and draws blood. But then - vision fuzzy and head still pounding - you get up and give it another go. Seconds later, you're back on the ground. This process continues until you look like a lumpier version of Grimace, the (in this case aptly named) McDonald's mascot, but for some unknowable reason, you don't stop. You never stop. I never stop. Because, you know, it's pretty great and stuff. And while a PC version's on the way, developer Vittorio Romeo got Cavanagh's permission to put his own open source spin on the eternally rotating formula.
I like the voice in Cavanagh's version better. Beyond that world-shattering alteration, though, this is pretty much Super Hexagon - just more open, on PC, and free. Happily, you can customize everything (rotation speed and, um, yep) and design your own levels, so it ought to be interesting to see what players come up with.
Cavanagh himself, meanwhile, is surprisingly cool with Open Hexagon's existence. OK, well, mostly. He explained on Twitter:
"I'm a little upset that he released it before I had a chance to release Super Hexagon on PC myself - but I'm basically alright with it! I've just checked it out there, and it's not bad at all - the harder octagon stage was pretty cool. I also like the death effect. I'm hoping Super Hexagon will be out on PC and Mac REALLY soon - I'm working flat out to make that happen!"
He's even posted about it over on Free Indie Games, so all's well that ends well, I suppose. It's quite well done, too. The music's suitably thumping, and the restart button triggers without pausing for so much as an instant. Which is good, given that it's something you'll be pressing several trillion times.