Consider multitouch. Conventional mouse-desktop thinking orients us to one pointer and a one-point interaction mode. "Normal Users" (aka, the Your Mom archetype) new to the touch experience and to Eliss almost always use a single finger to drag around the screen objects, switching to two only to pinch. But around level 3, the game ramps up in difficulty, and this is when the magic happens. The user starts falling behind. Without asking or thinking about it, nearly every single one of them suddenly starts using their other hand. Nobody told them it would work! These are users terrified of clicking the File menu, because it once ate their Word document. Experimentation has a huge mental inhibition, and yet touch is so intuitive it bypasses the block. I've asked all these users whether they noticed -- and while this isn't rigorous by any degree -- nearly all of them reported they did not. This is magic.
Thank you Steph Thirion, for hours of enjoyment in Eliss as well as a lovely natural experiment in UX.