It's surprising to me that you assert that a system which is simultaneously complex-enough to support Turing-complete calculation, and simple enough to be a "pi

It's surprising to me that you assert that a system which is simultaneously complex-enough to support Turing-complete calculation, and simple enough to be a "pick-up-and-play card game", is not carefully evolved. Fair shout on the number of banned cards, though - R&D and playtesting could definitely do better, there!