The goal is to:

• Take more pieces of the opposing team then they take from your team
• Put the opposing team's Top Board player in checkmate

The rules are by-and-large the same as Chess. Red moves first. One move per player per round.

Sides have up to 17 players. One player plays on a regular chessboard called the Top Board. The other up to 16 players each play on a second 64x64 board called the Lower Board. Each Lower Board player has a representing piece on the Top Board. The representing Top Board piece determines where on the Lower Board a player's pieces are positioned.

The Lower Board is a set of 8x8 areas. Each area is the Lower Board analog to one of the squares on the Top Board. When a piece is moved on the Top Board the Lower Board pieces represented by the Top Board piece are moved one 8x8 area per Top Board square to match the Top Board piece's new position. The 8x8 area that is the Lower Board analog of a representing piece's Top Board position is called the Home Area of the Lower Board player's pieces.

Pieces move as in Chess with the following exceptions for the Lower Board:

• Rook, Bishop and Queen may move more then 8 squares in a direction. I.e. they can leave their Home Area.
   
• Knight, King and Pawn may move to squares which are more then 8 squares from their starting positions. I.e. they can leave their Home Area.
   
• A player's set of pieces will be moved together, as a unit, when the piece representing the player on the Top Board is moved
   
• When a player's pieces are moved as a unit to match a move on the Top Board the new position of each Lower Board piece has the same position relative to the other pieces in the set. I.e. if a pawn is two squares to the right of another pawn played by the same player, in their new positions they will still be two squares apart on the same rank on files that are a multiple of 8 different from their original files.
   
• Any Lower Board piece that moves more then 8 squares from its starting position, moving outside its current home 8x8 area, may fall off the board if the player's representing piece on the Top Board is moved to a square that places the Lower Board piece on a nonexistent square. Pieces that fall off the board are removed from the game.
   
• Any Lower Board piece that is moved to match the representing Top Board piece may land on a square that is already occupied by a piece. If the occupying piece is of the opposing side the piece is taken by the moving side. If the occupying piece is of the same side the occupying piece is removed from the game.
   
• Lower Board players can be put in check; however, they do not have to defend their king.
   
• Lower Board players that are checkmated are removed from the game. Their representing Top Board piece is also removed from the game. (Note: this rule is not implemented in the current version of the game).
   
• Lower Board pawns may be promoted if they reach a square that is 7 ranks from the rank within the current Home Area where they would be placed if the game were starting. I.e. treating the Home Area as if it were a static chessboard promotion is the same as in Chess.
   
• When a Top Board piece is captured, the Lower Board pieces that Top Board piece represents are removed from the game. The Lower Board pieces are considered to have been captured by the opposing side.
   

Games play until the Top Board is in checkmate, or until all Lower Board pieces are captured or otherwise removed from play. Alternatively, a game creator can end a game. All games are scored according to the number of pieces captured by each side. A game that is ended early by the creator may be won by either side, or be a draw; however, each side is credited its full score. This is intended to reduce the temptation for a game creator to prematurely end a game when the creator's side is ahead. A future version of the game may require both sides to agree to end the game. Games where there are no moves for more then 20 rounds will end. (Note: this rule is not implemented in the current version of the game).

Features of Fogs of Otmoor (e.g. skips, delegation, different turn timing schemes, etc.) are considered to be implemented according to the rules of the game. However, they are not considered to represent formal rules and are subject to change.

Where actual game play differs from these rules (due to bugs, poorly written rules, unimplemented features or rules, etc.) the actual functioning of the game is to be considered correct. While updates to these rules should not substantially impact actual game play, these rules are subject to change for the foreseeable future while Fogs of Otmoor development continues.