Dohyō

Dohyō is an abstract game for two to four players themed on sumo wrestling. Players take turns pivoting and pushing their opponent's pieces in an attempt to push them out of the sumo arena, the dohyō. The rules are simple but lead to many interesting move sequences and surprises!

Components

Four sets of 12 like-colored pieces (Checkers or stones)
A 5 x 5 x 5 hexagonal game board with an embedded 4 x 4 x 4 grid.

Set Up

Standard two-player Dohyō is played on the a 4 x 4 x 4 hexagonal board, as indicated by a gold border line, using two sets of eleven pieces. The larger 5x5x5 hexagonal board is be used for three- or four-players games (which need play testing). See Figures 1 to 3 for set up placements.

Figure 1. Two-player set up

Figure 2. Three-player set up

Figure 3. Four player set up

Game Play

Starting with the lighter player, on each turn a player must perform a push or a pivot action. (See below for more details on these actions.) A player may not pass a turn. Player turns pass clockwise around the table, or alternate for two players.

Note that if possible, the push action is mandatory. If a player cannot push or pivot, that player is eliminated and will no longer take any further actions. The eliminated player's pieces remain on the board.

Push: A pair of adjacent owned pieces can push a single opponent piece. The opponent piece must be aligned with and adjacent to the pair and there must be an empty cell or the edge of the arena that is immediately beyond the opponent piece. All three pieces move a single cell in the direction on the push.

If the opponent piece is pushed out of the arena, it is captured and placed beside the board, on the capturing player's side of the board, as a reminder of who last made a capture. When another capture is made, the previously captured piece in gathered before the player who captured it. Players may not push their own pieces and may not simply slide their pieces without pushing an opponent piece. If multiple opportunities to push exist, the player is free to choose between them.
Pivot: If the active player cannot push an opponent piece, the player must perform a pivot move. A piece may move around an adjacent owned piece, in either a clockwise or counter-clockwise direction, any number of empty cells but may not pass over any cells outside the arena border or over any other piece. Moving a piece back to its starting location is not allowed.

Refer to Figures 4 through 7 for example push and pivot moves.

Figure 4. Pivot MovesThe yellow pieces indicated by the green dots can perform pivot moves. The moving piece must travel along the green arc passing through the piece. In this figure, there are no other pivot moves available. The red x's indicate that the brown and yellow pieces along the border may not revolve around each other because in doing so the moving piece would have to travel outside the arena border.

Figure 5. Push MovesThe green arrows identify all the possible push moves that can be made in this board state. Note that several pairs of pieces cannot push because there is no empty space behind the opponent's piece, see c4 to f7 for example.

Figure 6. Before a Push Move

Figure 7. After the PushNote that only two of the brown pieces move during the push. One brown piece is left behind. The pushed yellow piece is removed from the board and is out of the game and given to the brown player.

Winning the Game

There are three ways to win.

A player wins by knockout as soon as he or she pushes 9, 10, or 8 opponent pieces out of the arena for the two-, three- and four-players games respectively. In some cases, the opponent can throw in the towel (resign) when it's obvious who will win. Games can be shortened by choosing a lower capture requirement. For example, new players may want to play to just 6 or 7 pieces captured.
A player wins by submission if all his or her opponents are unable to move. This occurs when all the opponents' remaining pieces are isolated singletons, pinned, or captured. In Figure 4, Yellow wins because Brown is unable to move.
By termination, the referee calls the fight. If no captures are made for 24 rounds of play, the players are playing too defensively. In this case, the player who made the last capture wins the game at the end of the ninth round of passive play.

See Figure 8 to view a sample game.

Sample Game #2

Figure 8. Sample GameViewers can single step through the game or watch the game as a slide show.

Designer Comments

Dohyō has similarities to the game Abalone, a popular pushing game with its own steadfast following and dedicated web site. Abalone is a popular game despite the flaw of turtling or passive, repetitive play which can bring the game to a standstill when either player chooses to do so. My original design of Dohyō exhibited this same flaw. To counter defensive play, pushing went from being an option to a requirement. Of course, both players could decide to stall the game in the hopes of the other player will make a misstep, but if one player decides to play aggressively that player can more easily take control of the game. Dohyō becomes more transparent and predictable. It is hoped that players find this solution to be elegant and nearly sufficient.