RaiseChess – official rules

Version 0.3 · 28 September 2026 · Author: Mark Zavadckiy

RaiseChess follows the rules of chess, with two additions: some pieces are dealt face down, and the players bet chips on each game, heads-up. It is designed to be played online: the server deals the pieces, keeps them secret, checks every move and bet and decides the result.

Setup

Set up the pieces as in standard chess. (Optionally, the back ranks may be arranged as in Fischer Random Chess / Chess960.)
The deal. For each side, choose at random 3 of the 15 home squares on its first two ranks, excluding the king's square. (Variants: 4 or 5 squares.)
For each chosen square, draw the piece that stands there at random: queen, rook, bishop, knight or pawn, each with probability 1/5, independently. Repeats are allowed – a player may be dealt three queens while the opponent gets three pawns. The drawn piece replaces the piece of the standard setup on that square.
These are the player's pocket pieces. They stand face down: the owner's screen shows what they are, the opponent's screen shows only a piece of that colour.

The deal is not symmetric: each side draws its own pocket pieces, so one side may start with more material than the other. That is intended – it is what the betting is for.

Pieces and movement

All pieces, face down or not, move and capture exactly as their true type.
A pawn dealt onto the first rank moves one square forward (it has no double step from the first rank). Once it reaches the second rank by a normal move, it does not get a double step either. A pawn dealt onto the second rank keeps its normal double step.
Moving a face-down piece does not reveal it by itself. The opponent deduces it from the move: a diagonal move rules out rook, knight and pawn (unless it captured like a pawn), an L-shaped jump reveals a knight, and so on. When only one type is still possible, the piece is effectively revealed.
A captured face-down piece is revealed.
Promotion (to a queen) reveals the piece as a former pawn.
Castling follows Chess960 rules and is made with the outermost real rook on each side of the king, if that piece is really a rook and has not moved. Castling with a face-down rook reveals it.
Check, checkmate and stalemate are as in standard chess, judged by the server using the true types of all pieces. A move that would leave one's own king in check – possibly because of an opponent's face-down piece – is illegal: the program does not offer it. A player is told when his king is in check, even if the checking piece is face down.

Betting (heads-up)

Each player starts the match with 100 chips.
Blinds. Before each game White posts a big blind of 2 chips, Black a small blind of 1.
Blind levels. Optionally, as in heads-up poker tournaments, the blinds go up every N minutes from the start of the match (the online version offers 5, 10 or 15 minutes): 1/2, 2/4, 3/6, 5/10, 8/16, 12/24, 20/40, 30/60, 50/100. A new level applies from the next game. Rising blinds make a match finish in a predictable time.
Preflop. Before the first move, when each player has seen only his own pocket pieces, Black acts first: call (complete the blind), raise, or fold. If Black only calls, White has the option to raise before moving.
Each turn. At the start of each of his turns, before moving, the player to move may bet or check (simply make his move). A bet must be answered at once: the opponent calls (matches), raises, or folds. After a call, the player who bet makes his move.
Pot limit. A bet or raise may not exceed the size of the pot after the call. A raise must be at least the size of the previous bet or raise, and at least the big blind. At most 4 bets and raises per turn.
All-in. No one bets more than the opponent can match. A player may call all-in for less; the unmatched excess is returned.
Fold. A fold gives up the game: the opponent takes the pot at once.

End of a game

Checkmate wins the pot.
Stalemate splits the pot.
Showdown. In the showdown version (below), if neither player has folded and there is no mate, the game stops after a set number of moves. All pocket pieces are turned face up and material is counted: queen 9, rook 5, bishop 3, knight 3, pawn 1. The side with more material takes the pot; equal material splits it.

Two ways to end a game are chosen before the match:

Showdown after move N (the default): the game stops after each side has made its Nth move – 20, 30 (standard) or 40 – and goes to the material count above.
To mate: no move limit; a game ends only by checkmate, stalemate or a fold.

The current version has no fifty-move or repetition rule; in the showdown version the move limit ends long games.

The match

Chips carry over from game to game and colours alternate, so the blinds alternate too. The match ends when one player has no chips left. Two scores are kept: chips won and lost, and games won and lost.

A version without chips (only the face-down pieces, with the same showdown) is a good way to learn the game.

Notes

Reading a range. The core skill is inference. At the start each of the opponent's pocket pieces can be any of five types, so three pocket pieces carry 5³ = 125 equally likely deals (about 7 bits of uncertainty). Every move by a face-down piece removes the types that could not have made it. A strong player also asks the second-order question: which moves keep his own pieces ambiguous and which give them away. The online version marks, for each move of a face-down piece, whether it keeps the secret or reveals the piece.

Why betting works here. Because each player knows something the other does not, a bet carries information and can be a bluff. A player dealt three pawns in place of a queen, rook and bishop may fold preflop for one chip, or bet as if his pocket pieces were strong and try to win the pot without a showdown.

Material at showdown also makes long positional play count for less than in chess; the betting decides how much each game is worth.

Over-the-board play. The game is meant for online play. At a physical board it needs an arbiter who sees both sides, as in Kriegspiel: someone has to deal the pocket pieces, refuse moves that are illegal because of an unseen piece, and keep the chips. A simpler over-the-board version without an arbiter is possible if the check rule is dropped and capturing the king wins the game; the deal can then be made with dice and the pieces marked underneath. That version has not been tested.