I wish I could take credit (I wasn't on the game engine but rather the matchmaking/store/chatting part), but I was working with some real geniuses there (technical and creative).
Still, by far and away the most interesting Java project I've ever worked on. I'd never heard of so many enterprisey technologies around a game before (unfortunately, I don't know what would be covered under my NDA, so I probably can't say much more than that :).