I somehow came across the Kloonigames website yesterday and spent a good long while there. It’s the website of a student programmer who has written many games in a week or less. Pick a game from the square thumbnails on the right-hand side. My favourites are Humpsters, Bloody Zombies, and Crayon Physics.
Here’s a video of the sequel, Crayon Physics Deluxe, which looks totally stunning. Don’t let the sequel’s sophistication ruin your impression of the original game though – it’s brilliant and eerily calming.