Dan Vs. This Game. It's a side-scroller with just three levels, each based on a different episode of the show. While it isn't too difficult in theory, I had a hard time beating it simply because of all the enemies making my computer lag. That, and jumping is not as easy as it should be. Just trying to get from one platform to another slowed me down considerably. But even so, it took less than an hour to play the whole thing.
Still, I enjoyed playing it, even if level three's super-lagging got on my nerves. The level transitions are fun, and level themes work well with the show's style.