"But I unfortunately was born at the wrong end of Time..."
Merlin's Chain is a board game where two players compete to win a game of four-in-a-row where the pieces can be played out of order.
Components. An 8x8 board and sixty-four unique game pieces. Each piece has an unplayed (gray) side and a played (color) side and a number from 1 to 64 on both sides. The white pieces have odd numbers, and the green even.
The picture shows the 18 piece in its face-down position (left) and its face-up position (right).
Setup. Players sit side-by-side with the board in front of them. The side of the board closest to the players is the bottom, with columns extending away. Assign one player Green (controls the green pieces) and the other White (controls the white pieces). Put all pieces on the board in their unplayed positions (gray side up) and configure a valid board. Green goes first.
To configure a valid board, move any unplayed pieces on the board so that the numbers in each column are increasing from bottom to top. You may move your opponents unplayed pieces, but you may not move any played pieces.
The picture shows one starting configuration. However, any configuration in which every column has increasing numbers is valid.
On your turn. You may configure any valid board you like, and then flip one of your unplayed pieces to its played position (color side up). Then it becomes your opponent's turn.
The image to the left shows a valid play of the 17 piece.
Validity is shown by the arrangement of the other unplayed
pieces, in which each column is in ascending order.
The image to the right shows a set of invalid plays of the 17 piece.
In each of these positions, there is no arrangement of the
unplayed pieces that has every column in ascending order.
Winning the game. A set of four played pieces of the same color that form a contiguous vertical, horizontal, or diagonal line is called a chain. A chain's rank is the highest numbered piece in the chain. When all pieces are played, the player with the chain of lowest rank is the winner.
A green chain of rank 42
A white chain of rank 31
A green chain of rank 50
A white chain of rank 45
A completed game in which White has 8 chains of ranks 37, 39, 43, 49, 53, 55, and 61. Green has 4 chains of ranks 34, 42, 52, and 60. Green is the winner because the chain of lowest rank (34) is Green.
A partial game in which White is guaranteed to win. You can often determine the outcome of a game well before all the pieces have been played.
A game can end in a draw under two conditions: if all pieces are played and neither player has a chain, or if the players discover that a mistake was made and there is no way to configure a valid board given the locations of the played pieces -- every turn it is both players' responsibility to ensure that the play is valid.