Doom 4

Another wonderful game from Pixeljam - this one is called Dino Run. The gameplay is very simple: the asteroid apocalypse has arrived in the Cretaceous Period and all the dinosaurs are fleeing the doom.

You play one such dino, and run from left to right, leaping over your fellow dinos, eating those small enough, catching rides on terradactyls and surfing the wave of molten doom.

This is pixel art turned up to the max - the gameplay is simple, but the detail and range of interactions belies any screenshot - those Pixeljam guys obviously have real love for this game. There's even multiplayer, and the ability to buff your dino's stats with points awarded from successful runs.