The Singularity is here, and it's available on iOS and Android for free.
It's a sort-of game called Polyfauna, designed by Radiohead and the design studio Universal Everything. You traverse a series of procedurally-generated landscapes, using your device's gyroscopes to alter direction and altitude. Swiping a finger across the screen creates simple, vaguely prokaryotic-looking life forms. When you're ready to move on, you can navigate to a flashing red transition point and you'll be teleported to another zone with a different environmental theme.
I've only played with it for a little bit, but even on a phone the experience is deeply immersive (headphones are a must). The Stanley Donwood-inspired landscapes are both sere and beautiful, with lots of weird ambient effects. It really does have the eerie quality of Gibson's cyberspace. And after a while, you start to wonder if you're really all alone in there...