Chess

This page tries to explain chess-specific features of ghosty's chess game which includes

• Chess-specific options of the /chess application command
• How to make chess moves
• Notation of chess moves
• Chess variants supported by ghosty

tip

If you want to know how to start or end a game, or how to see your stats and ranking, please see our general help for two-player games.

Getting Started

Options

The /chess application command has two chess-specific options:

• variant - allows you to select a chess variant (see here for more details)
• flipping_board - in each turn, the board is flipped so that the player who is about to move is always on the bottom of the board. This option allows you to disable this feature.

Moves

To make a move, you simply send a message with the move in the appropriate notation. An example of such a move could be e2e4. See the notation section for an explanation of the notation.

Notation

ghosty supports two notations both of which are commonly used: UCI (short for Universal Chess Interface) and SAN (short for Standard Algebraic Notation). Each of these notations has its own advantages and disadvantages, and new players may find one easier to use than the other.

Chess Board

• The eight files are indicated by the small letters from a to h.
• The eight ranks are numbered from 1 to 8.

These squares are used to indicate moves in SAN and UCI.

UCI notation

UCI notation is the easiest notation for new players to learn. It is used primarily by computer chess programs to communicate with each other, but it is also sometimes used by human players.

In UCI notation, the move is described in the following form:

<origin square><destination square>

Here are examples of moves written in UCI notation:

e2e4
e7e5
g1f3
b8c6
f1c4
a7a6

SAN notation

SAN notation is the most common notation used by human players. It is more compact and readable than UCI notation, but it can be more difficult for new players to learn.

In SAN notation, the moves are written in the form

<piece><destination square>

where the piece is abbreviated to a single letter (as shown in the table below).

Piece	Abbreviation
♙ Pawn
♘ Knight	N
♗ Bishop	B
♖ Rook	R
♕ Queen	Q
♔ King	K

Pawns are not indicated by their first letter, but are recognised by the absence of such a letter. Examples: the moves are written e5, d4, a5.

Here is an example of three moves written in SAN notation:

e5
Nc6
Bc5

In the case of ambiguities (multiple pieces of the same type moving to the same square), you have to disambiguate the move by adding the file or rank of the origin square. For example, if you have two knights on the board, and you want to move the knight on c3 to d5, you would write Ncd5.

Special notations

In addition to the basic move notation, there are also some special cases that require a specific notation. For example, using SAN, castling is written as O-O for kingside castling and O-O-O for queenside castling. This is shown in the table below, along with the notation for other special moves such as promotion:

Move	UCI notation	SAN notation
Kingside castling	e1g1 (white) e8g8 (black)	O-O
Queenside castling	e1c1 (white) a8d8 (black)	O-O-O
Promotion	g7g8q (example)	h1=Q (example)

In SAN, there are also some optional special notations for

• x = captures
• + = check
• # = checkmate
• e.p. = captures ‘en passant’

Chess Variants

The /chess slash command allows players to select from several different chess variants, each with its own unique set of rules and strategies. Here is a brief overview of the four popular chess variants that ghosty supports:

Standard Chess

Standard chess is the most widely known and played form of chess. It is played on an 8x8 board with 16 pieces per player: one king, one queen, two rooks, two bishops, two knights, and eight pawns. The goal of the game is to checkmate the opponent's king, which occurs when the king is in a position to be captured (in "check") and there is no way to move the king out of capture (mate).

Chess960

In Chess960 (also known as Fischer Random Chess), the starting position of the pieces on the players' home ranks is randomized, with the following restrictions: the bishops must be placed on opposite-colored squares, the king must be placed between the rooks, and the knights must be placed on the outermost squares of the player's home rank. This means that there are 960 possible starting positions in Chess960, hence the name.

In Chess960 castling moves are represented as king moves to the corresponding rook square.

Suicide Chess

Suicide chess is a variant in which the objective for each player is to lose all of their pieces.

• Capturing is compulsory, so if a player has the opportunity to capture one of their opponent's pieces, they must do so.
• Additionally, the king has no royal power and can be captured just like any other piece. This means that there is no concept of check, checkmate, or castling in Suicide Chess.
• Stalemate is a win for the stalemated player (the player with no legal moves).

King of the Hill

In King of the Hill, the primary goal is not to checkmate the opponent's king, but to move your own king to the center of the board. The game ends immediately when a player moves their king to any of the four central squares. Games can still end in the traditional ways of checkmate, stalemate and time-out.

Racing Kings

Racing Kings is a chess variant where the objective is to move the king to the eighth rank. Players have the same view of the board and start with mirrored piece setups, with white moving first. In this version, all pieces move as in standard chess, but it is illegal to put the opponent's king in check or to move into check.

Atomic Chess

Atomic Chess is a variant of standard chess in which captures result in an explosion that removes all affected pieces from the board. In this variant, the game can end not only in checkmate, but also if one of the kings is blown up.

Additional considerations and specifics:

• The ability to escape checkmate by blowing up the enemy king first
• The king being unable to make captures
• Pawns are only affected by explosions if they are directly involved in a capture
• For en passant captures, the explosion occurs on the square where the capturing pawn lands