About SUMO, from BoardGameGeek:
In SUMO, you try to use card play to push your opponent from the game.
To set up, place the sumo wrestlers card in the center of the sumo ring. (The sumo ring has only three positions: left, center, and right.) One player sits on the left of the ring, the other on the right. Deal each player a hand of eight cards from a deck that contains 20 cards: 1-5 in four suits.
Each player plays and reveals a card, with the high card playing first in the first trick; if the cards are tied, repeat this action until one player wins or all eight cards have been revealed, in which case you shuffle and re-deal.
The first player plays a card, then the other player must follow suit, if possible. If the second player is off suit, the first player wins; if not, whoever played the higher card wins. In either case, the winner pushes the sumo wrestlers card away from them, then leads to the next trick.
If the sumo wrestlers are ever pushed out of the ring, the pusher wins the game. If this doesn't happen, the winner of the final trick wins the game. However, a player can win earlier through one of three "sumo moves":
Abise-taoshi: Crushing the opponent with your weight, which in game terms means playing a 4 in the same color after a lead 1.
Hikiotoshi: Using the opponent's momentum to knock them down, which in game terms means playing a 1 in the same color after a lead 5.
Wucchari: Throwing your opponent out of the ring, which happens should you play an off-color 2 when the sumo wrestlers card is on the edge of the ring near you.
