muds. if he likes games, actual games, if he cares about the mechanics. muds will do it. easy to get into, easy to progress to programming, and tons more depth the more he gets into it. if he can't do without the graphics, could always help him build an mmo, i'm pretty sure there are a few open source ones out there. either way, the toolset only goes so far and instils a hunger for more creative and mechanical control that only programming gives.