Ask HN: Resources for a fun programming competition

I'm trying to organize a fun competition at my company for one of our internal events.

It's just for fun, not recruitment or anything of the sort.

We make videogames, so obvious things would be a game competition (suggestions on very easy, very fast to iterate frameworks are appreciated) and a rendering competition (e.g. something like https://www.shadertoy.com/) or an optimization one.

Another fun thing would be something like Crobots or any of the more modern variants http://en.wikipedia.org/wiki/Crobots

But I wanted to see if it was possible to organize something more like a creative puzzle. First thing that comes to mind is a "CrackMe" but most can be quite daunting for a diverse audience, they are usually very technical for people with already some reversing background.

Any other ideas/tips/links?