diff --git a/CHESS_RULES.md b/CHESS_RULES.md new file mode 100644 index 0000000..99baaba --- /dev/null +++ b/CHESS_RULES.md @@ -0,0 +1,518 @@ +# Chess + +## Introduction + +You can play Chess in X-Decor-libre! + +While the game of Chess is well-known and widespread and its +rules are well-documented all over the Internet and elsewhere, +the devil still lies in the detail. + +In X-Decor-libre, the game of Chess is closely modeled after +the FIDE Laws of Chess from January 2023. However, for a +computer version of Chess, there are still some details +that might need explanation. + +## Objective + +Chess is played between two players on a chessboard. One player plays +with white pieces while the other one plays with black pieces. +The goal of the game is to put the king of the opponent under attack +in such a way they have no legal move. This is known as ‘checkmate’. +It is not allowed to put one’s king in danger, to leave him in danger +or to capture the opponent’s king. + +## How to play + +You need a chessboard to play. Craft yourself a chessboard like this: + + BWB + sss + +B = Black Dye +W = White Dye +s = Wooden Slab (from apple tree) + +Place the chessboard and examine it. You will see a close-up of the chessboard. + +### The Chess interface + +On the screen that pops up, you can choose to play against the +computer (Singleplayer) or another player on the server (Multiplayer). +You may also use the multiplayer option to play against yourself. +The computer player is quite weak. + +Click on the corresponding button to start the game. + +Once the game has started, you see the following things: + +To the left, the large chessboard consisting of 8×8 dark and white squares. +The pieces are put on the chessboard. If there is no active game, +the chessboard is empty. + +During a game, the interface has the following meaning: + +Above and below the chessboard, plaques show the name of the players. +Above the chessboard is the player playing Black and below it +the player playing White. +An arrow left of the plaque shows whose turn it is. The name plaques +may also show the “game status”, such as victory, checkmate (=loss), +draw, being “in check”, etc. + +On the right side, a list of moves that have been made is shown. +It is written in a figurine long algebraic notation (see appendix). + +The two boxes below the list of moves is where all the captured pieces +go. This has no gameplay significance but it may serve as a visual +aid to see how badly hurt the player's “armies” are. This section +may change + +The top right corner is used for starting a new game. Press +“New Game” to start a new game. This ends the current game. + +The bottom right corner right corner is used for special +player actions, such as resigning or claiming a draw. + +Note that during a game, the buttons only work for the two players +playing Chess. They don’t work for anyone else. + +## The rules of Chess + +### Starting a game + +Select Singleplayer or Multiplayer. In Singleplayer, you choose +the color you play as by clicking the corresponding button. + +White always plays first. + +In multiplayer, anyone can make the first move. +The player making the first move as White will play as White, +the player making the first move as Black will play as Black. +After that, the players are “locked” to their colors and +nobody else can play as White or Black. + +### The chessboard + +The chessboard is a board of 8×8 squares alternating between light +and dark squares. Each square is either empty or holds exactly one +chess piece. + +### The Chess pieces and how they move + +Each player starts with the same pieces on opposing sides of the board, +only their color is different. + +There are 4 types of moves you can make: + +* Normal move: You pick up the piece and place it to an empty square +* Capturing move: You pick up the piece and place it on top of an opposing piece + Your piece will land on that square and the opponent’s piece is removed +* En passant: Special capturing move of the pawn (see below) +* Castling: Special king+rook move (see below) + +It is not possible to place your piece on your own pieces. +It is not possible to capture a king or your own pieces. +Any square on which a piece could capture another piece in theory +(even if it is actually empty) is considered to be “attacked”. + +For most pieces, the rules for making a normal move and +a capturing move are identical. Only for the pawn it is different +(read below). + +If the square of the king is attacked, he and the player playing him +is considered to be in “check”. +If a player is in check, any move which would put or leave the own +king under attack is not allowed. + +#### How to actually move + +Each move can be made by either clicking on the piece and then clicking again +on the destination. The destination is either an empty square or a square +occupied by an opponent’s piece (which will be captured). +You can also do the same via drag-and-drop. + +Once you made a valid move by placing the piece to its destination, it is +final and cannot be taken back. This ends your move and it’s your +opponent’s turn (exception: promotion, see below). + +If you pick up a piece and put it back, nothing happens, it is still +your turn and you can still do your move normally. Also, if you try +to make an invalid move, nothing happens as well. + +(Nerd info: For the purposes of the FIDE Laws of Chess, pieces are never +considered “touched” here. Thus, article 4 of the FIDE Laws of Chess has +no effect.) + +#### Rook + +The rook looks like a tower and can move to any of square that lies +in a straight horizontal or vertical line from it. +It cannot move beyond pieces that are in the way. + +The rook can move on a square occupied by an opponent, which +w + +The rook may be involved in Castling, see “King” below. + +#### Bishop + +The bishop can move to any square on a diagonal line from it. +It cannot move beyond pieces that are in the way. + +#### Queen + +The queen combines the powers of the rook and bishop and can +move to any square in a straight horizontal, vertical +or diagonal line from it. +It cannot move beyond pieces that are in the way. + +#### Knight + +The knight looks like a horse and can move to any square closest to +it that is not in its same horizontal line (also known as “rank”), +vertical line (also known as “file”), or diagonal of the board. +To illustrate this: + + ..X.X.. + .X...X. + ...n... + .X...X. + ..X.X.. + +In this diagram, “n” represents the knight and the Xes are all the +possible squares it can theoretically reach. The dots are empty +squares. + +Unlike the other pieces, pieces are never “in the way” of the knight. +You might say the knight can “jump over” them, if you will. + +#### King + +The king can move exactly one square in any direction: horizontally, +vertically or diagonally. Also, the king can never move to any square that +is attacked by an opponent’s piece. + +The king also has a special move called “Castling”. + +##### Castling + +Castling is a special move in which two pieces move at once. +Both the king and a rook move horizontally from their starting positions. +The king will move two squares horizontally and a rook will be +moved next to him. + +Each player has two possible castling moves available, involving each +of the 2 starting rooks. + +Castling has several conditions: + +- The king must not have moved yet +- The rook you wish to castle with must not have moved yet +- All of the squares between king and rook must be empty +- The king must not be under attack +- The king’s destination as well the square it crosses must not be under attack +- You can castle only horizontally + +If all the conditions are met, here’s how you castle: + +Place the king two squares towards the rook you want to castle with. +This square is where the king will end up. The rook will then +automatically move towards the king and “jump” to the square +behind the king, from the rooks viewpoint. + +**Remember**: You *must* move the king (not the rook) if you want +to castle. If you move the rook instead, this is considered +to be a regular move of the rook alone. + +#### Pawn + +The pawn has various ways to move. +The pawn has a “walking direction”, it walks and captures towards +the opponent’s side (i.e. the side on which the opponent’s +pieces have started). + +The pawn’s basic moves are: + +1. Single step: The pawn moves one step vertically towards the + opponent’s side. It is not possible to walk backwards. +2. Double step: Like a single step, but it moves two squares instead. + This is only possible from the pawn’s start position. + +In both cases, the destination square must be empty as well as any crossed square. +The pawn cannot capture by a single or double step, however. + +The capturing move of the pawn is different. To capture, the pawn has to +move one step diagonally towards the opponent’s side, either left or right. + +To illustrate, in the following diagram, the X’es represent the +squares attacked by a white pawn (w) and a black pawn (b): + + .X.X..b.. + ..w..X.X. + +##### En passant capture + +An en passant capture is a pawn move that is available if a pawn +of the current player stands on a square left or right from an +opposing pawn that has made a double step in the previous move. + +In this situation, the first pawn may move as if the second pawn +had made a single step instead. This will be considered as a +capturing move and the opposing pawn will be removed from the board. + + +Consider this example: Here, “w” represents a white pawn, “b” a black pawn and “.” +an empty square. White moves upwards and Black downwards. Consider this starting +position: + + b. + .. + .w + +Now, White does a double step: + + bw + .. + .. + +Black decides to do an en passant capture. For this, the black pawn moves one +diagonal step towards the square just crossed by the opponent. The white +pawn is captured and removed. + + .. + .b + .. + +Remember! An 'en passant' capture is only possible in the move directly after +a pawn’s double step. So if the chance for a particular en passant capture +is not taken, it will be gone from that point on. + +##### Promotion + +When a pawn reaches the other end of the chessboard (from its viewpoint) +it will be promoted. A promotion is considered to be part of the move. + +When promotion happens, the boxes where normally the captured pieces go +will turn into a prompt. The current player must choose a new +piece to replace the pawn with: +A queen, rook, bishop or knight of the same color. +Just click the corresponding button. These buttons only work for the +current player. Promotion is mandatory and no other moves are possible +until it is completed. + +Once a piece was selected, the pawn will be replaced replaced, which +immediately activates its powers. This ends the move. + +### The end of the game + +There are various ways for the game of Chess to end. A game always +ends in victory of one player, or in a draw. + +#### Checkmate +Checkmating your opponent is the primary goal of Chess. +The player who has checkmated the opponent king wins the game and ends it. + +You are checkmated when it’s your turn, your own king is in check +(i.e. under attack) and you have no valid move available. +This immediately ends the game and your opponent wins. + +#### Stalemate +If it’s a player’s turn, but they have no possible move and their +king is not in check, the game immediately ends in a draw. +This is called a “stalemate”. + +#### Resign +During the game, the possibility of resigning arises. Resigning +basically means “giving up” and this leads to an instant loss +and the victory of your opponent. +Resigning is available after one’s name has been recorded on +the name plaque. Resigning is possible even when it’s not your turn. + +To resign, click the skull icon in the bottom right. + +#### Dead position +If during the game, on the board there are only the following pieces left, +the game ends in a draw: + +* king versus king +* king versus king and bishop +* king versus king and knight +* king and bishop versus king and bishop, and both bishops stand on squares of the same color + +This is called a “dead position”. For example, a board with only a white +and a black king is a draw. + +NOTE: In general, a dead position is any position from which neither player can +give checkmate, no matter how they move, but only those 4 cases above +lead to an instant draw in X-Decor-libre because it is tricky to +determine whether any position is “dead”. + +However, dead positions are still guaranteed to end the game eventually +due to the 75-move rule. + +#### 50-move rule +If in the last 50 consecutive moves of each player, no piece was +captured and no pawn was moved, the player whose turn it is can invoke +the 50-move rule to draw the game instantly. + +When it’s your turn, and you believe your *next* move will satisfy +the condition of the 50-move rule, you may also invoke this rule +to draw the game, but in this case, you still have to make the move. +If this move satisfies the 50-move rule, the game is drawn. +But if not, this counts as a normal move, your turn ends and the +game continues as normal. + +A button on the bottom right will appear when this rule is available. +The button is not shown when there are too few such moves for this +draw claim to be successful. + +The icon represents a barricade, as if the game of Chess itself +has been blocked. This one will instantly draw the game. +If you still would have to make the game-drawing move, the +icon represents half a barricade. +Note the tooltip. + +Note the latter icon is no guarantee you can actually draw the +game in the next move, only that such a draw claim is plausible. + +#### 75-move rule +If in the last 75 consecutive moves of each player, no piece was captured +and no pawn was moved, the game automatically ends in a draw. + +Exception: If the last move has lead to a checkmate. In this case, checkmate +takes precedence. + +#### Threefold repetition rule +If the current position has appeared at least 3 times in the game +the current player can invoke the threefold repetition rule to draw +the game instantly. + +Two positions are considered to be the same “same” if a position in which +the chessboard has the same pieces of the same color on the same squares, +it is the same player's turn, the castling rights are the same +and the vulnerability of pawns to en passant captures (if any) is the same. + +Pawns are considered “vulnerable” to an en passant capture immediately +after a double step turn, no matter if is actually in danger of +being captured that way. + +This rule can also be invoked when you think your *next* move will +lead to the 3rd (or more) repeated position in the game. This +works similar as for the 50-move rule. + +Like for the 50-move rule, a button appears on the bottom right +once this rule can be invoked. + +If the 3 same position has already occurred, the icon will +represent 3 chess squares stacked on top of each other. +If the game-drawing move still has to be made, the top +square is a “ghost square”. + +#### Fivefold repetition rule +If the same position (as defined above) has appeared at for +least 5 times, the game is drawn. + +#### No agreeing to draw + +Unlike in other Chess programs, the players cannot agree to draw. + +#### Game result + +Once the game has ended, the game result is shown on the name plaques of the +players as well in chat (to the players only). From this point on, everyone +(even spectators) can start a new game with “New Game”. + + +## Resetting the chessboard + +While a game of Chess is ongoing, the chessboard can’t be dug and the game +can’t be stopped by other players. But to prevent two players blocking a +chessboard forever, there is a 5-minute timer. If no player makes a move +for 5 minutes, then the chessboard can be reset and dug by anyone. + + +## Appendix + +### The Chess Notation + +The list of moves is in a special notation called “algebraic notation”. There are many +variants of it, so this section explains what it means in X-Decor-libre. + +This mod uses a longform figurine algebraic notation. “figurine” means that +icons are used for the chess pieces. “longform” means the start +and end coordinates are shown in full. + +Square coordinates are important in any Chess notation. In algebraic notation, +each square is assigned coordinated with a letter from a to h, +followed by a number from 1 to 8. +Provided that the player playing White is on the “bottom” side of the chessboard, +the squares are numbered from the bottom left square in ascending order. +The horizontal lines (“ranks”) are numbered 1 to 8, starting from the bottom. +The vertical lines (“files”) are numbered a to h, starting from the left. +So from White's viewpoint, the bottom-left square is a1. The square above it +is a2, then a3, a4, ... a8. The square right of a1 is b1, then c1, d1, ... h1. +The top-right square is h8. + +(Note that on a real chessboard, all of the coordinates are flipped from Black’s viewpoint +because the board is rotated 180° from their view. In X-Decor-libre, this does not +matter because the board is always aligned the same way.) + +In the list of moves, each line shows 3 things: Move number, white’s move, black’s move (if made). +The move number is a simple counter that increases after each move of *both* players, starting by 1. + +In the notation, a move by a single player is called a “halfmove”. The two moves +of each White and then Black are called a “fullmove”. + +#### Normal moves + +Normally, a halfmove is written like this, in this order: + +1. Symbol of moved piece (called “figurine”) +2. Start coordinates, a dash or cross, destination coordinates +3. “e.p.”, if it was an en passant capture -OR- symbol of piece to which a pawn was promoted to + +For number 1, the symbol is only shown if the piece is not a pawn. +For number 2, the syntax for normal moves is like: “a1–a2”. This means the piece was moved from a1 to a2. +The dash means it was a normal move. +For capturing moves, the dash is replaced with a cross “×”. If it was an en passant capture, then +“ e.p” is appended, like so: “a5×b4 e.p.”. +If a pawn was promoted, the symbol of the new piece is appended. +The figurines are always of the color of the player. + +Both halfmoves on a line are separated by spacing. + +#### Castling + +When a player castles, it is notated the following way: + +* “0–0” for castling with the rook on file h (“kingside castling”) +* “0–0–0” for castling with the rook on file a (“queenside castling”) + +#### Game completion + +If the game completed, the end of the game showing the result is listed in a final separate line as: + +* “1–0” if White won +* “0–1” if Black won +* “½–½” in case of a draw + +#### Example + + 1. d2—d4 e7—e6 + 2. ♔e1–d2 ♛d8–h4 + 3. d4–d5 e6×d5 + ... + 8. d8×d8♖ ♞b8-c6 + 9. e2–e4 d4×e3 e.p. + +Explanation of the moves: + +* 1.: First fullmove: White moves pawn from d2 to d4, Black moves pawn from e7 to e6 +* 2.: Second fullmove: White moves king from e1 to d2, Black moves queen from d8 to h4 +* 3.: Third fullmove: White moves pawn from d4 to d5, Black moves pawn from d6 to d5 and captures +* 8.: Eight fullmove: White moves pawn from d7 to d8, captures a piece and promotes it to rook, Black moves knight from b8 to c6 +* 9.: Ninth fullmove: White moves pawn from e2 to e4, black moves pawn from d4 to e3 and captures en passant + +#### Other symbols + +Other symbols are not used. So there are no special symbols for check and checkmate and no comments for moves considered good or bad. diff --git a/README.md b/README.md index 44d0481..c300b5a 100644 --- a/README.md +++ b/README.md @@ -32,7 +32,7 @@ blocks with special features: in some food items. Collect the soup with a bowl * Lever: Pull the lever to activate doors next to it * Pressure Plate: Step on it to activate doors next to it -* Chessboard: Play Chess against a player or the computer +* Chessboard: Play Chess against a player or the computer (see `CHESS_RULES.md`) The radio and speaker are purely decorative and have no special functionality. @@ -101,6 +101,7 @@ Maintenance updates: * Add tooltip extensions for some interactive items (uses `tt` mod) * Add crafting guide support for `unified_inventory` mod (honey) * Rope no longer extends infinitely in Creative Mode +* Added manual for chess in `CHESS_RULES.md` #### List of replaced files