You might have heard of Canabalt by now... it's getting quite a reputation these days, and with good reason. Originally a free browser-based PC game, it's made the leap to the iPhone, and quite successfully, by all accounts.
Leaping is what Canabalt is all about. In what is one of the simplest games you'll ever play, the game sees you on the rooftops of a crumbling city, trying to get away from disaster. I'm pretty sure that, as in most games of this type, that's not possible, and you live by your high score/farthest travelled distance.
And that's it. You use one button to jump, and you can't control your character in any other way. It's extremely refreshing, and the game turns out to be very, very addictive.
Flyyyyy... fly, my beauty!
Canabalt has an appealing retro graphics style... it uses a black/white/grey palette, and the main character is very Commodore 64-ish. Once it gets moving, you'll be drawn in to your thrilling escape effort, which rivals anything from blockbuster movies in its scale.
There's really nothing more to say about the game... it really is that simple. But what's also simple is the fact that Canabalt is a really well done game that's very addictive and well worth your time. Play the free version first, and then if you like it, pop onto your iPhone and pay the £1.79 to have it on you at all times. See how good you are. The farthest I've managed to get is 6088 metres.