Maybe it's been mentioned before, but just in case: Take a look at Unity 3d. (Get it here: http://unity3d.com/) - that's a pretty powerful game engine. The standard version is free and will suffice, it is very easy to learn. It's kinda like an universal level editor. Coding is done in javascript or C#, but there are tons of examples to get started (Official tutorials: http://unity3d.com/support/resources/tutorials/). And the community is pretty active aswell, so he'd be able to get help on the (Official forum: http://forum.unity3d.com/ - User wiki: http://www.unifycommunity.com/).

IMHO, the biggest achievement of Wikipedia is that it raised the bar considerably for other, traditional media. Here in Germany, the 'Brockhaus' encyclopedia recently announced that it won't be publishing books anymore, but change to an online model. (I think that was discussed here a few weeks ago.) So either this new online edition is much better than Wikipedia, or it'll go bust pretty soon. Same holds true for most 'traditional' media, especially newspapers; if they don't offer content that is much, much better than what is aviable for free online, they won't last. And it seems to me that the best guarantee to that end is editorial quality. So bring it on! Time will tell and user will decide which model is going to last.