This wiki will try to explain the rules of Biyi without using some of the unique terminology which is specific to the game. R.
A game turn consists of a movement phase and a jump phase.
In almost all circumstances, a player's pieces normally move horizontally, or forward. Occasionally, as part of a stack, a player's pieces can also move backwards.
1. Moving Up (Climb)
A player may move up the top piece in a stack, or a single one of their pieces forward or horizontally on top of another one of their pieces, if they are at the same level and orthogonally adjacent.
2. Moving Down (Descend)
A player can move a piece forward or horizontally down from the top of a stack into an orthogonally adjacent space, whether they move on top of one of their own pieces, one of their opponents pieces, or onto the board.
A player may slide a single piece forward or horizontally on the board into an orthogonally adjacent space, if that space is unoccupied.
The top piece of a stack controls its movement, while the bottom piece of the stack determines the direction in which the stack may slide. A stack may always slide into an adjacent space, if it is at a lower level. A player may slide a stack forward, if the top and bottom pieces belong to the same player. A player may slide a stack backwards, if the top piece belongs to the player, and the bottom piece belongs to their opponent. Any pieces in between the top and bottom slide along with the stack. The only time that a player's pieces may move backwards is as part of a stack. If a stack slides onto another piece, or stack of pieces, only those pieces in the first stack above the level of the pieces in the second stack slide. In this case, the bottom most piece of the group of sliding pieces controls the direction of movement.
For example, if only the top piece from a stack slides, then it cannot be moved backwards. If a stack of five pieces moves onto a stack of two pieces, only the top three pieces will slide, and the color of the third piece will determine whether the stack can slide forwards or backwards.
Adjacent Uniform Stacks (Dragons):
If at the beginning of a player's turn, they have two or more stacks of three or more of their own pieces which are orthogonally adjacent to each other, they lose the game, if that same condition exists at the end of their turn. It is, however, legal to have mixed stacks of pieces adjacent to or separating uniform stacks of 3 pieces.
The jump phase is the second part of a players turn. If after making a legal movement the resulting stack has more than three of a player's pieces, then they must jump. The player must move the top piece in the stack to an orthogonally adjacent space without moving backwards. When jumping, the top piece can be moved on top of a flock of any number of levels. If after jumping, the resulting flock also has more than four of the players pieces, the player must jump again.
A stack or a piece located in the river must always be connected (adjacent) to another stack or piece located outside of the river, or to a piece in the river which is. This chain may not be broken, if it would leave a piece orphaned in the river. However, pieces may be moved to other locations that maintain the chain.
A player cannot make a move which leaves pieces in the exact same position in which they were in on the previous move.
No pieces may be moved on to one's own bird token.
If a player ends two consecutive turns with two or more orthogonally adjacent uniform stacks of three or more of their pieces, they lose the game.
The game is declared a draw, if the board's pieces repeat themselves.
A player wins the game, if they are able to move onto the opponent's bird without having any of their own adjacent uniform stacks.
A player loses, if they have no legal moves.
The game ends in a draw, if all of the pieces are in the exact same position as they were at the end of the previous turn.
Position cards change the starting arrangement of the board. Use one card for players to have a symmetrical board. Use two cards for each player to have unique starting positions.