Tai Shogi
Sam had apparently been studying shogi, and it took me a few games to figure out a response to his opening last night. When I did, it was a long, slow, crushing victory as my forces eliminated his rook-side before dropping his captured rook in for the kill. So, it was an encouraging end, even if I did lose most of my games.
Anyway, I just ran across a page describing Tai Shogi, probably the largest natural chess variant. The board measures 25×25, and each player starts with 177 pieces of more than 100 different types, including the Drunk Elephant and the Reclining Dragon. The royal piece is the "Emperor", who is also the most powerful, being able to move to any undefended square. Now, there's a game.