This app was mentioned in 3 comments, with an average of 1.33 upvotes
I remember a Cartoon Network TV ad that had an Adventure Time app/game that let you draw out levels and import them: Adventure Time Game Wizard
It seems to feature a game engine called Pixel Press which also has it's own 'draw your own game' deal: Pixel Press - Floors
Pixel Press was on kickstarter last year it seems. No idea if this really is what you are looking for but I hope it at least helps.