http://fuse.microsoft.com/kodu/ if you have kids or are interested in this new type of interface for creating simple games, then go ahead and download kodu for the PC, in case you didn't on the 360. I m downloading it right now and I look forward to trying it out, until then, feel free to post your comments and experiences with it
It's pretty straight forward. I've made a lot of random stuff on the 360 with it. (Basic shooters w/patterns. Simple concept of a puzzle/adventure game. Lolo 1 clone w/a few levels.) I suggest looking at the sample games to see how a lot of stuff works. Or going through one of the tutorials maybe. It really is pretty straight forward and simple to use. Of course there's a limit to what you can do, but it really is a nice introduction to the basic concepts of variables, events and interaction.