Super Hexagon's success on iOS has taken developer Terry Cavanagh very much by surprise. The game, an expansion on Cavanagh's original Pirate Kart entry Hexagon, sold more than 10,000 copies in its first three days on sale in the App Store -- a total that the dev never dreamed was possible for a seemingly niche experience. Not that it surprised the rest of us. With such iconic titles as VVVVVV, At a Distance, Don't Look Back and Pathways already under his belt, it seems like Cavanagh can do no wrong. Cavanagh's first foray into the world of iOS development went off without a hitch, thanks to his smooth gelling with the Adobe AIR environment, and a concept that struck a chord with the iOS audience. Players rotate an arrow around a hexagon-shaped playing field, dodging through gaps and second-guessing morphing shapes to survive for as long as possible before hitting a wall. "Making Hexagon for the Pirate Kart didn't get the game out of my system," Cavanagh tells Gamasutra. "It's something I kept thinking about for months after I'd released it. I felt like I'd stumbled onto something really primal, and I wanted to spent some time exploring it properly." He adds, "I didn't expect it would turn into quite as big a project as it did, though." The original was released just over six months ago, and can still be played on Cavanagh's website. Most notable about Super Hexagon is its similarities to Cavanagh's other most popular title VVVVVV. Both games feature rather masochist gameplay, killing players over and over again at high speed, but allowing quick restarts to ease the potential frustration. While you might assume that Cavanagh purposely makes his games hair-pullingly difficult, he says this honestly isn't really the case -- rather, he just tries to balance the difficulty to levels that he believes to be the most enjoyable. "I guess it just sort of happens naturally," he notes. "Most of the time I spent working on Super Hexagon, I spent tweaking things, playing it again, gradually improving it little by little with each iteration. It feels the way it does because that's what feels good to me." Cavanagh's next port of call is to provide PC and Android builds of Super Hexagon before diving back into work on his Nexus City RPG with fellow indie dev Jonas Kyratzes. Nexus City definitely has one of Cavanagh's longer cycles for a game, having been in development since the start of 2010. Whatever the plan, it will no doubt receive as much attention as his prior works when it's eventually ready.