Will he be programming a web game or a desktop game? If it's not a web-based game you should request this thread be moved to the programming forum. Just use the red and white triangle icon to the left of your original post and let the mods know you want it moved.
There's no much you can really do, game programming-wise, with web technologies like JavaScript, but there's much more you can do with C++, Java, DirectX, etc. Finding something for an 11 yo is kind of tough too. What computer skills / programming skills does he currently have? A lot of game programming deals with advanced math skills so that's why I'm curious and expecting for him to be able to do.