Starting out as a Kickstarter project, the original Pixel Press Floors is a game that is available for iPad and allows anyone to draw levels for a platform style game using symbols on grid paper. Then using an iPad, take a photo of that paper and the symbols get translated into various obstacles and paths. Once your level looks how you like, it can be shared with other people who can also play that level.
Join Finn and Jake for a positively algebraic experience
Pixel Press has teamed up with Cartoon Network to create an official Adventure Time game in which Finn and Jake discover a magical sketchbook which brings to life anything drawn in it. There are free downloads of templates for use with the app that include a how-to guide for level creation. And did I mention that the bad guy is voiced by Weird Al Yankovic? Because that is pretty awesome, too.
I haven't been able to spend a lot of time playing with it yet, but so far it's a lot of fun and pretty engaging. So if you are someone who has a jones for the old style platformers, or perhaps have some children with regular access to an iPad, this is definitely an app you should investigate further.