Dice Chess

[Marco Greco]

Anyone ever play dice chess?

I introduced this to my son, as he was losing interest in the game. It introduces some luck back into the game, and since I am slightly better than my 7 year old (for now), he has a better chance of beating me. We only played two games, and I have the rules below from wikipedia, but have made 3 main changes (marked Greco variation), and am claiming it as the Greco variation of Dice Chess.

We have not played using the addition and subtraction of dice, but I added this in, to increase the possible piece moves, making it closer to a real chess game. The idea behind being able to make any legal move when you are in check, is again to make it more like a real game of chess. I have also removed the idea of capturing the king. Appreciate any feedback:

The players alternate rolling the dice and, if possible, moving. On each of the dice, the one represents a pawn, two a knight, three a bishop, four a rook, five a queen, and six a king. The player may move either of the pieces indicated on the two dice. For example, a player rolling a one and a two may move either a pawn or a knight. A player who rolls doubles (the same number on both dice) may play any legal move. Greco variation allows you to add or subtract dice, to increase the possible pieces to move. (If you roll 1 and 5, then you can move a pawn (1) or a queen (5) or a king (5+1=6) or a rook (5-1=4). Otherwise, standard chess rules apply, with these exceptions:
-a player who has no legal move with either of the pieces indicated by the dice loses that turn (passed turn);
-if castling is otherwise legal, a player may castle upon rolling a four, six, or doubles; Greco variation allows you to add or subtract dice, so if adding or subtracting the dice equals 4 or 6, you can also castle.
-an en passant capture of a pawn is possible only if the player rolls a one, or doubles, immediately once the opportunity for the en passant capture arises;
-in Greco variation, a player who is in check, does not roll the dice, and can just play a legal response to that check (capturing the checking piece, moving the king, or interposing a piece);
-except in the unlikely event that the game ends in a draw pursuant to the standard rules of chess, the game ends when one player checkmates the opponent's king.

[Hugh Brodie]

Re: Dice Chess

We used to play a more simplified version - with one die. You made a move with a piece corresponding the dice roll - if possible/legal; otherwise you were forced to "pass". A check was responded to by rolling the one die until a legal move could be made (unless there was only one forced move - why bother rolling?). [Alternate rule: the "checked" player only rolls once. If the roll doesn't parry the check, he has to hope his opponent doesn't make a roll enabling him to "capture" the King.]

[Kevin Pacey]

Re: Dice Chess

I once played against a friend using just one die, as Hugh describes, except in some/most games we agreed that if a die showed a piece type to be moved that no longer could legally do so (or no such piece was left on the board) the player was allowed to roll again - or else, for example, die roll 1-3 corresponded to a pawn move and die roll 4-6 corresponded to a king move, if a player only had pawns and his king left on the board.

[Paul Bonham]

Re: Dice Chess

Anyone ever play dice chess?

I introduced this to my son, as he was losing interest in the game. It introduces some luck back into the game, and since I am slightly better than my 7 year old (for now), he has a better chance of beating me. We only played two games, and I have the rules below from wikipedia, but have made 3 main changes (marked Greco variation), and am claiming it as the Greco variation of Dice Chess.

We have not played using the addition and subtraction of dice, but I added this in, to increase the possible piece moves, making it closer to a real chess game. The idea behind being able to make any legal move when you are in check, is again to make it more like a real game of chess. I have also removed the idea of capturing the king. Appreciate any feedback:

The players alternate rolling the dice and, if possible, moving. On each of the dice, the one represents a pawn, two a knight, three a bishop, four a rook, five a queen, and six a king. The player may move either of the pieces indicated on the two dice. For example, a player rolling a one and a two may move either a pawn or a knight. A player who rolls doubles (the same number on both dice) may play any legal move. Greco variation allows you to add or subtract dice, to increase the possible pieces to move. (If you roll 1 and 5, then you can move a pawn (1) or a queen (5) or a king (5+1=6) or a rook (5-1=4). Otherwise, standard chess rules apply, with these exceptions:
-a player who has no legal move with either of the pieces indicated by the dice loses that turn (passed turn);
-if castling is otherwise legal, a player may castle upon rolling a four, six, or doubles; Greco variation allows you to add or subtract dice, so if adding or subtracting the dice equals 4 or 6, you can also castle.
-an en passant capture of a pawn is possible only if the player rolls a one, or doubles, immediately once the opportunity for the en passant capture arises;
-in Greco variation, a player who is in check, does not roll the dice, and can just play a legal response to that check (capturing the checking piece, moving the king, or interposing a piece);
-except in the unlikely event that the game ends in a draw pursuant to the standard rules of chess, the game ends when one player checkmates the opponent's king.

Marco, you could teach your 7 year old son something about handling probabilities if you used the dice a little differently.

In the case where only one die indicates the piece that can move, the probability for being able to move a given piece type is always 1/6. What if instead you used the SUM of two dice to determine which piece type can move?

Something like this:

Sum of 2 Dice Roll		Probability			Piece To Move
-------------------------------------------------------------------------------
	3 or 11			4/36  (1/9)			Q		
	2,3,11 or 12		6/36  (1/6)			R		
	5 or 9			8/36  (2/9)			B		
	6 or 8			10/36 (5/18)			N		
	4,7 or 10		12/36 (1/3)			P

I've left Kings out because we could have a rule that says one can always choose to move the King. But you don't have to, you can pass your move if the dice roll indicated a piece type you can't move and you'd rather not move your King. But for endgames, this additional rule will be very helpful to keep the endgame moving along.

Now, we have different probabilities for each piect type. The Queen has the least probability of being able to move, and the Pawn has the most probability. Each player could now choose moves based on probabilities, much like poker players choose whether to fold, bet, call, raise (and by how much) all based on mathematical probabilities.

Also, on a chess variant forum, regarding Dice Chess, I saw this comment:

"Awesome rule variant for this: Every time you want to move a piece, you move it, and then roll it. It becomes whatever kind of piece you rolled for its next turn."

This makes the probabilities even more interesting: we could have a chart like this (use scroll bar to see rightmost portion of chart):

Sum of 2 Dice Roll		Probability			Piece To Move		Replacement Piece After Move
-------------------------------------------------------------------------------------------------------------------------
	3 or 11			4/36  (1/9)			Q					P
	2,3,11 or 12		6/36  (1/6)			R					B
	5 or 9			8/36  (2/9)		        B					N
	6 or 8			10/36 (5/18)			N					R
	4,7 or 10		12/36 (1/3)			P					Q

So the Pawns get the most moves, but turn into Queens after each move, and the Queens have the least number of moves, but they turn into a Pawn after moving.

You'd have to have a lot of extra Queens! (and other piece types).

[Marco Greco]

Re: Dice Chess

Thanks for your reply...I like the idea of keep rolling until you get a piece you can move, since missing your turn takes the game farther away from orthodox chess. The advantage of using two dice, is that when you roll doubles, you get to make a move with any piece, more like a real game.

[Kenneth Regan]

Re: Dice Chess

The equations in my chess research papers produce the probability values to place on the moves available in any position, such that "Dice Chess" with those probability settings (a few 20-sided dice like my children use in role-playing card games will work closely enough) becomes a close approximation to human chess of any desired Elo level.

That is, real chess is Dice Chess. Just like real physics is dice physics...