Four-Player Chess/Notation

Algebraic notation
For four-player chess the same algebraic notation as for regular chess can be used:
 * K = king
 * Q = queen
 * R = rook
 * B = bishop
 * N = knight
 * No letter is used for pawn moves.
 * When the move is a capture, an x is inserted between the origin and destination square.
 * If two pieces of the same type can move to the same square, the file or rank of origin (or both, if necessary) are added after the piece's letter.
 * Pawn promotion is indicated by appending =Q to the move (or, in case of underpromotion, =N, =B or =R).
 * Kingside castling (short castle) is notated as O-O and queenside castling (long castle) as O-O-O.
 * Check is indicated by appending + to the move and in case of double and triple check ++ and +++, respectively.
 * Checkmate is indicated by appending # to the move.
 * Piece manoeuvres are notated as the piece letter followed by the origin square, any intermediate squares and the destination square, separated by a hyphen, e.g. Qg1-k5-g9. In case of manoeuvres involving captures, the moves are written in full, separated by hyphens, e.g. Nk12-Nxm11-Nxn9.
 * Diagonals are notated as start and end square, separated by a hyphen. Diagonals are always considered from left to right, hence the start square is the leftmost square, i.e. start and end are in alphabetical order in terms of files. For example, "e14-n5 diagonal" and not "n5-e14 diagonal".

Other common annotations include:
 * ! = good move
 * !! = excellent move
 * ? = bad move
 * ?? = blunder
 * !? = potentially interesting move
 * ?! = dubious move

Long algebraic notation
Alternatively, long algebraic notation can be used for clarity. In long algebraic notation both the origin and destination square are indicated, separated by a hyphen, e.g. Qn8-m9. When the move is a capture, the hyphen is replaced by an x and the letter of the captured piece is also included, e.g. Qg1xQn8+.

Colour indication
Players commonly prepend moves with one letter to indicate the colour of the piece, if that may not be clear from the context: r for red, b for blue, y for yellow and g for green. For example, bQxh14+ means blue queen takes h14 and rQxn8+ means red queen takes n8.

Forsyth–Edwards Notation 4 (FEN4)
FEN4 is a standard notation for describing a particular four-player chess board position. It can be used to start a game from a specific position. The FEN4 consists of seven parts, separated by a hyphen:
 * 1) Player to move, indicated by a capital letter (R, B, Y or G)
 * 2) Player eliminated (comma-separated, 0/1)
 * 3) Castling availability kingside (comma-separated, 0/1)
 * 4) Castling availability queenside (comma-separated, 0/1)
 * 5) Points (comma-separated)
 * 6) Halfmove clock. This is the number of halfmoves since the last capture or pawn advance. This is used to determine if a draw can be claimed under the fifty-move rule
 * 7) Piece placement from Red's perspective. Starting from the 14th rank and going back to the first rank, each rank is described by a comma-separated line indicating the occupation of the squares within that rank from the a-file to the n-file. Pieces are identified using algebraic notation (with P = pawn) and the colour of the pieces is indicated by prepending a lowercase r, b, y or g, for red, blue, yellow and green, respectively. The number of empty squares between occupied squares is noted using digits 1-14. The ranks are separated by a forward slash and the 3x3 corners of the 14x14 board are counted as empty squares.

Starting position
The normal starting position in FEN4 is as follows: R-0,0,0,0-1,1,1,1-1,1,1,1-0,0,0,0-0- 3,yR,yN,yB,yK,yQ,yB,yN,yR,3/ 3,yP,yP,yP,yP,yP,yP,yP,yP,3/ 14/ bR,bP,10,gP,gR/ bN,bP,10,gP,gN/ bB,bP,10,gP,gB/ bK,bP,10,gP,gQ/ bQ,bP,10,gP,gK/ bB,bP,10,gP,gB/ bN,bP,10,gP,gN/ bR,bP,10,gP,gR/ 14/ 3,rP,rP,rP,rP,rP,rP,rP,rP,3/ 3,rR,rN,rB,rQ,rK,rB,rN,rR,3

Portable Game Notation 4 (PGN4)
PGN4 is a standard notation for recording a complete four-player chess game, i.e. the moves and related data. The PGN4 consists of tag pairs and movetext.

Tag pairs
The tag pairs indicate game related data. The tags start with a left square bracket, followed by the tag name, followed by the tag value in double quotation marks and closed by a right square bracket. At the very least, the 'Variant' tag must be included, to indicate whether the game is a Teams game or a Free-For-All (FFA) game. Common tags are the following: Other optional tags are possible.
 * Variant: main variant, i.e. Teams or FFA
 * RuleVariant: one of the many variants on the rules, e.g. king of the hill, N-check, 960, etc.
 * CurrentMove: ply-variation-move, e.g. 5-2-3 means fifth ply, second variation, move three
 * StartFen4: the starting position in FEN4
 * Red: red player name (similarly, Blue, Yellow and Green)
 * RedElo: red player rating (similarly, BlueElo, YellowElo and GreenElo)
 * TimeControl: e.g. 1+15D
 * Date: date and time the game was played
 * Site: location where the game was played, e.g. website, if online
 * Result: 1-0 if Red and Yellow won, 0-1 if Blue and Green won, 1/2-1/2 in case of a draw or player: points for each player, in case of FFA
 * Termination: reason the game ended (e.g. resignation, timeout or simply game over)

Movetext
After the tag pairs the movetext follows, which describes the actual moves of the game. The movetext uses long algebraic notation and includes move number indicators, i.e. the full move number (not quarter-moves) followed by a single period. Moves are separated by two periods. Variations are added in round brackets and comments are inserted in curly brackets. The reason of elimination of a player is included on the player's final turn, i.e. # for checkmate, R for resignation and T for timeout.

Example PGN4
An example of a game recorded in PGN4: [GameNr "519084"] [Result "0-1"] [Termination "Checkmate. 0-1"] [Variant "Teams"] [Red "ClashRoyale12345"] [RedElo "2204"] [Blue "MANISPUGO"] [BlueElo "1528"] [Yellow "nutsyci"] [YellowElo "2368"] [Green "GDII"] [GreenElo "1857"] [TimeControl "1+15 delay"] [Site "www.chess.com/4-player-chess"] [Date "Wed Nov 28 2018 01:28:10 GMT+0000 (UTC)"] [CurrentMove "29"] 1. d2-d4 .. b8-c8 .. k13-k11 .. m8-l8 2. d4-d5 .. b4-d4 .. k11-k10 .. Qn8-m8 3. e2-e4 .. Qa7-b8 .. g13-g12 .. Nn5-l6 4. f2-f4 .. Qb8xf4 .. Qh14-f12 .. Nl6-k4 5. i2-i4 .. Qf4xh2+ .. Qf12-b8+ .. Nk4xj2+ 6. Kh1xQh2 .. Ba9xQb8+ .. Rk14-k11 .. Qm8xi4 7. g2-g3 .. Bb8xg3+ .. Rk11-j11 .. Qi4-h3+ 8. #