DVONN is a two-player strategy board game in which the objective is to accumulate pieces in stacks. It was released in 2001 by Kris Burm as the fourth game of the GIPF project.

Rules

Equipment
DVONN is played on a board with 49 spaces. The board has a hexagonal layout 5 hexes wide. One player has 23 black pieces to play, the other 23 white pieces. There are also 3 neutral red pieces, called DVONN pieces.


Object
The object of the game is to control more pieces than the opponent at the end of the game.


Placement phase
The game starts with an empty board, and proceeds in two phases. During the first phase the players place their pieces on the board, starting with the three red DVONN pieces. Pieces can be placed on any unoccupied space. White starts, and the players alternate. So Black is the first to place a piece of his own color. The first phase ends when all pieces are placed on the board, filling it completely.


Movement phase
The second phase involves the building of stacks of pieces (a single piece is also considered a stack) by moving stacks onto other stacks. A stack is controlled by a player if his color is on top. A stack is immobile if it is surrounded by 6 neighboring stacks. The black player will have the first move in this phase. Any mobile stack of height n (with n>0) can be moved in any one of the 6 directions by exactly n spaces by the player controlling it, if it lands on another stack. Single DVONN pieces can not be moved, but they can be part of a stack. After each move all stacks which are not connected via a chain of neighboring stacks to any stack containing a DVONN piece are removed from the board.


Passing and game end
A player who has no legal move must pass, and a play may only pass when no legal move is available. The game ends when both players have no legal moves. All stacks controlled by one player are collected into one tower. The winner is the player with the higher tower.


Strategy

Placement phase
Many beginner players place their pieces at the start of the game without a clear objective. However, placement is as major a factor in winning as the movement phase.

Pieces should be placed with three main goals in mind: spaces by Dvonn pieces, spaces by the side, and general density. The first objective is to place pieces by DVONN pieces, thereby keeping them safe from potential separation. Keeping at least three pieces by each Dvonn piece helps defend them from potential attack. Next, pieces that are surrounded cannot move; therefore, having pieces along the side to start the game is valuable. Such pieces should also be in postion to free other pieces on the inside. Finally, lumping groups of one's own pieces together is usually poor strategy. It is desirable to capture on every move, prevent a capture, or at least take a DVONN piece; keeping all of one's pieces together often makes this difficult. Spreading pieces out across the board also increases the chance of maintaining a short (and therefore highly mobile) stack into endgame, where it may be moved into position for a crucial capture.

It may also be possible to string a line of one's own pieces across the board up and down. Play almost always separates along this line; pieces on one side of a string that has no DVONN piece are usually doomed.


Movement phase
The first few moves should correct any place where your position must be fixed: helping or moving pieces that could become isolated and moving outside pieces in order to give inside ones mobility.

Capturing pieces that could capture a DVONN piece can be important, as a moving DVONN piece controlled by the opponent can isolate a large group of pieces. However, mobility is the most important aspect of DVONN; one needs to keep one's options open. Building a tall stack early in the movement phase is a mistake.

Taking a DVONN piece is especially desirable if it is possible to move it toward one's own pieces and away from one's opponent's. However, every capture counts, so big captures and maintaining mobility is more important than just taking Dvonn pieces.

After move 70 (about 20 moves into the movement phase) the board clears and settles. It becomes much more important to look ahead to see how every move affects the overall situation. Tall stacks are very hard to move, so they should be formed next to (or on) DVONN pieces and out of line of potential captures.