Copyright (c) 2003 Mark Steere
Impasse is played on a 8x8
square board with the following setup:
Black lies in the bottom, green in the top of
|SOLDIER - A soldier
slides diagonally forward any number of empty cells.
|KING - A King slides diagonally
backwards any number of empty cells.
|TURN - On each turn,
each player must do one of the following actions:
|Move a friendly piece
|Swap a friendly King with a friendly
soldier, provided that they are adjacent and the King is in front
of the soldier.
|IMPASSE - If a player
does not have a valid move, he must do one of the following things: (i)
remove one of his soldiers from the
board, or (ii) demote
one of his Kings to a soldier.
|After the impasse, it is the next
player's turn. So, each player can only apply the impasse rule
once for each turn.
|This rule only applies at the
beginning of the turn. If a player makes a move which
deprives him of future moves, this does not entitle him to the
|PROMOTION - If a friendly soldier
moves into the player's last row, it will be promoted to a King and
the player must remove another friendly soldier from the board (using
checkers, this means that the removed soldier will be on top of the
|If there are two soldiers in the
last row (yes, it's possible), the player must immediately promote
one and remove the other.
|If there is one soldier in the last
row, and no other soldiers on the board, then the soldier remains uncrowned.
|DEMOTION - If a friendly King
moves into the player's first row, it will be demoted to a soldier.
|GOAL -.Wins the player
that removes all, or all but one of his pieces.
|A promoting example
Black can promote the bottom soldier
sliding it to cell  and thus removing another black soldier.
Black's turn. Since he cannot move, the
impasse rule is applied and Black may remove one soldier (or demote one
of his Kings). The best option is the bottom soldier, because it
provides the best chance of keeping the impasse on the next turn.
More information can be found here.