Video Games: Leveling Up: Game Development
If your library has a computer lab, snag it for an after school game development program. Gamestar Mechanic is my favorite because it doesn't require a client to be installed or any registration beyond a username. Kids play through levels to understand good game design and accumulate sprites to use in their own creations. I included a simple level that I created as an example. KODU (developed at Microsoft) and SCRATCH (developed at MIT) are also excellent.