Wikinauts — Multiplatform Scribblenauts
This is an idea I've had since the first Scribblenauts game was released: A community-driven version. The basic premise is identical to that of Scribblenauts: solving puzzle-based levels using just about anything you can think of by summoning items, NPCs, etc by writing the name down. For example, the objective is to get a star out of a tree. You could summon a lumberjack to cut the tree down, or a saw/chainsaw/axe/etc to cut it down yourself. Or you could summon a ladder to climb up into the tree. Or a jetpack, helicopter, wings... The possibilities are endless. The point of difference between Scribblenauts and my idea of Wikinauts is the social, community-driven aspect.