Gosu is a simple game library written in Ruby by Julian Raschke. While it may not be your first choice for AAA games, it is a great framework for beginners (and who knows- maybe if enough of us use it we will get a AAA game some day ?). If you’d like to look at the source code or contribute, you can find it here.

Gosu already has a really good set of tutorials for Windows, Mac, and Linux.

I’ve assembled a small group of code snippets that may be a helpful reference if you’re starting out: