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This page is written by the game's inventor, Michael Nelson.


Decima was a finalist in the 10-Chess Design Contest. It features quite a few tens: 10x10 board, 10 non-pawn piece types, and a unique objective: getting pieces worth 10 or more points on the tenth rank.



There are 10 piece types in this game (excluding Pawns) which consist of the four elemental pieces King, Knight, Bishop, and Rook and the six two-element combination pieces. Each piece has a point value, with the weaker pieces having the higher point values and the stronger pieces having the lower point values.

King (10 points)
Moves as in orthodox Chess, but is not royal, so it can be exposed to capture. Castling is not possible.
Knight (9 points)
Moves as in orthodox Chess.
Bishop (8 points)
Moves as in orthodox Chess.
Rook (7 points)
Moves as in orthodox Chess.
Duke (6 points)
Moves as the King or the Knight.
Pope (5 points)
Moves as the King or the Bishop.
Seneschal (4 points)
Moves as the King or the Rook.
Palladin (3 points)
Moves as the Knight or the Bishop.
Marshall (2 points)
Moves as the Knight of the Rook.
Queen (1 point)
Moves as the Bishop or the Rook.
Pawn (no points)
Moves without capturing one square straight forward. Can move two squares straight forward without capturing if the first square is empty with one exception: a Pawn may not move across a square attacked by an enemy Pawn. The Pawn captures one square diagonally forward. An unpromoted Pawn has no point value. Pawns promote to Kings. A Pawn which reaches the tenth rank remains a Pawn, but its owner may promote it in place as his move on any subsequent turn.


FIDE Chess rules apply except as indicated in these rules.

The object of Decima is to have one or more of your pieces whose point values total 10 or more on your tenth rank at the beginning of your turn.

Moving a piece to your tenth rank which causes your point total to reach or exceed 10 is equivalent to check--your opponent must capture one of your pieces and bring your total down to 9 or less on his turn. If your opponent cannot make such a capture, this is equivalent to checkmate and you win.

The capture of an opponent's piece on its tenth rank is a suicide capture--the capturing piece is also removed from the board. This applies whether or not the opponent has 10 points on the tenth rank.

Capturing your opponent's last piece wins.

A suicide capture with you own last piece loses.

A suicide capture of your opponent's last piece with your own last piece is a draw.

Stalemate and triple repetiton are draws just as in orthodox Chess.

The 50-move rule applies exactly as in orthodox Chess.


The levelling effect is present in Decima in a peculiar way: the low point value pieces are the more powerful. They have more mobility and an easier time reaching the tenth rank; but they have little value for actually carrying out the win. Get the Queen, Marshall, and Palladin to the tenth rank and that's 6 points--you still need another piece. On the other hand, a King can seem to take forever to reach the tenth rank but can win all by itself. Most wins in practice involve two pieces.

Much strategy will revolve around finding the right moment to exchange or even sacrifice a high material value/low point value piece in order to allow weaker/higher point value pices to break through.

It is usually good strategy to give "check" often--as this requires the opponent to make a suicide capture, it will break down his defenses. Defense revolves around trying to keep any enemy piece from reaching the tenth rank.

On the other hand, sometimes the best defense is a good offense--if the opponent is overlooking his own defense while carrying out his all-out attack, you might find an opportunity for a quick counterattack. Sometimes sneaking a single piece down to the tenth rank is sufficient to turn the game around.

Much more strategy and tactics remain to be discovered.

This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.

By Michael Nelson.
Web page created: 2005-05-01. Web page last updated: 2005-05-01