I recently signed up for the STEM video game challenge (http://stemchallenge.org/Default.aspx), but I'm at a lack of inspiration for a simple, playable, game idea, so I need help. Any suggestions for anything doable with C++ in a 2 month period?

Criteria pl0x? As in, 2D or 3D, specific genre? Or go wild?

2D or 3D, doesn't really matter, as long as I can create it within 2 months. Genre, preferably educational but puzzle, sidescrolling would also be nice. You can basically do anything for this competition, but I have no idea where to start with coming up with a game idea.

I recently signed up for the STEM video game challenge (http://stemchallenge.org/Default.aspx), but I'm at a lack of inspiration for a simple, playable, game idea, so I need help. Any suggestions for anything doable with C++ in a 2 month period?

Well, it is a game design challange where you need to proof your skills/creativity, not ours. When you can't come up with an own idea, just clone a game idea of a simple game you like....

How about one of those little evolution games - you generate a batch of randomized plants or creatures out of 2d or 3d polygons and some mathematical info about the color of each polygon. You let the player pick which two are the parents of the next generation. And for a small improvement on similar games, give the player a little inventory where they can store 6 or so plants/creatures they particularly like, and can optionally use those as one or both parents.