This is... A very late reply, I know, but what can you do, I didn't really think this one through before but I now have. I like the cardverse idea, and I'm actually planning it (and will continue planning once I get home, which is after about three days or so). I think I'll show my plan here or make another topic about it when I'm done, so you and others could comment on it and say if it's good enough or should I change something about it.
Also, I like the chess idea, and I could probably use as a base those little RP's that we have had before and then work on that. I'll put my plan of that RP AU somewhere as well, separately from the cardverse AU.