Apparently, Hard-or-whatever mode will "change the topography of the levels a lot" and offer different puzzles. In a game built entirely around environmental puzzles like that, with no enemies, that's about the only way a hard mode could be instituted without awful time limits. "It's more like playing a new set of levels than getting the normal ones in a harder format," he said. It sounds like some alteration of the base levels to create new challenges. Maybe Hard Mode is the regular game, inverted? Although looking at the above screenshot, maybe not.