# Rules of play **Version:** v009 — Draw Verdict Wording This document completely describes how to play this version of the game. A reader with only this document and the interface can play a full game against another player, and the two of them can determine who won. ## The game Hexagonal chess, after Wladyslaw Glinski. Two players, White and Black, share one screen and take turns with the same pointer. The board is not a square grid: it is a large hexagon tessellated into **91 hexagonal cells**, arranged in eleven vertical files. Cells come in three tones, repeating across the board, which mark the three colour bounds a bishop can never leave. **Files and ranks.** The eleven files are lettered **a b c d e f g h i k l** from left to right — the letter *j* is skipped, as in Glinski's own notation. The files have different heights: 6, 7, 8, 9, 10, 11, 10, 9, 8, 7, 6 cells, so the outer files are short and the central f-file is the tallest. Within each file the cells are numbered **from 1 upward starting at the White (bottom) end**. A cell is named by its file letter and its number: `a1`, `f11`, `k7`. Ranks can reach two digits (`e10`, `f11`). White moves first. Players alternate, one move per turn. Passing is not allowed. ## Starting position Each side has eighteen pieces: one king, one queen, two rooks, two knights, **three bishops**, and **nine pawns**. White's pieces stand on: - **King** g1, **Queen** e1 - **Bishops** f1, f2, f3 (stacked on the central file, one on each of the three cell tones) - **Knights** d1, h1 - **Rooks** c1, i1 - **Pawns** b1, c2, d3, e4, f5, g4, h3, i2, k1 (a shallow chevron across the board) Black's position is the exact 180° rotation of White's through the centre cell f6, so the two armies are perfectly symmetric. The interface sets up the board; you do not place pieces by hand. ## Objective Checkmate the opposing king: attack it so that the opponent has no legal move that removes the attack. Delivering checkmate wins the game immediately. ## Adjacency Every cell has two kinds of neighbour: - **Six orthogonal neighbours** — the six cells that share an *edge* with it. These are the rook directions. Within a file, the orthogonal neighbours directly above and below are the same file, one rank up or down. - **Six diagonal neighbours** — the six cells that share only a *vertex* with it. These are the bishop directions. A bishop direction always keeps a piece on cells of a single tone; a rook direction moves between tones. ## Piece movement - **Pawn** (circle): moves one cell straight forward — toward the opponent's side — to an empty cell. It never moves two cells, and it never moves backward. It captures onto either of the **two forward diagonal cells** (the diagonal neighbours to the forward-left and forward-right). White's forward is up the board; Black's is down. - **Knight** (L shape): leaps to one of up to twelve cells — the cells reached by one orthogonal step followed by one diagonal step outward, so that the leap lands on neither a rook line nor a bishop line from its origin. It jumps over anything in between. - **Bishop** (triangle): moves any number of empty cells along a diagonal (vertex-sharing) direction. Confined for the whole game to cells of its one tone. - **Rook** (square): moves any number of empty cells along an orthogonal (edge-sharing) direction. - **Queen** (asterisk): moves any number of empty cells along any orthogonal or diagonal direction. - **King** (cross): moves one cell to any of its **six orthogonal neighbours**. A piece captures by moving onto a cell occupied by an enemy piece, which is removed. No piece except the knight may pass through an occupied cell. You may never capture your own piece. ## Promotion A pawn that reaches the **far edge** — the border of cells on the opponent's side, from which it could advance no further — promotes at once to a queen, rook, bishop, or knight of its own colour, at its owner's choice. The interface presents the choice when it occurs. ## Special moves that do not exist here There is **no castling**, **no en passant**, and **no two-cell pawn advance**. These moves of square chess have no counterpart in this version. ## Check and legality A king is **in check** when an enemy piece attacks its cell. You may never make a move that leaves your own king in check; the interface enforces this by offering only legal moves. If you are in check, every legal move available to you resolves the check. ## How a game ends The interface detects each of these conditions automatically and announces the result in the status line. That announcement is the authoritative verdict. **Decisive result:** - **Checkmate.** The player to move is in check and has no legal move. That player loses; the other player wins. **Draws (neither player wins):** - **Stalemate.** The player to move is not in check but has no legal move. - **Fifty-move rule.** Fifty consecutive full moves pass with no capture and no pawn move. - **Threefold repetition.** The same arrangement of pieces, with the same player to move, occurs for the third time. - **Insufficient material.** Neither side retains enough material to ever deliver checkmate — king against king, king and a single knight or bishop against king, or kings with only bishops that all stand on one colour tone. ## Determining the winner Play until the status line announces a result. "Checkmate — White wins" or "Checkmate — Black wins" names the winner. "Stalemate" or "Draw" means neither player has won. The verdict is computed from the position and displayed; it is always definite. Checkmate is reachable — Glinski's hexagonal chess has been played to decisive results for decades — so the game always terminates in one of the announcements above. ## The interface Move by dragging a piece to a highlighted destination, or by clicking a piece and then clicking a destination. When a piece is selected, its legal destinations are marked: empty destinations are shaded, and a cell you can capture on is ringed. **New game** starts over; **Undo** takes back the most recent move by agreement of the players. The game is local: both players share one screen. **Forced moves.** When the player to move has exactly one legal move, that move executes automatically after 800 ms, with no announcement. It appears in the move list identically to a hand-played move. Because a whole sequence can consist of successive forced positions, this may advance several moves in a row without any input, one step per 800 ms. Auto-execution never changes which move is legal or how the game ends; it only removes the wait when there is no choice to make. If **Undo** returns the game to a position where the side to move still has only one legal move, that move executes again after 800 ms. The guarantee holds however the forced position is reached — by ordinary play, by **Undo**, or by editing the move list (below): whenever the side to move has exactly one legal move, that move executes after 800 ms. **The move list.** Each move is recorded in this version's coordinate notation — the piece letter (none for a pawn) followed by the destination cell, with `x` for a capture and `=Q`/`=R`/`=B`/`=N` for a promotion. Each entry in the list is editable in place, a carry-over from the square version. Editing replays the list from the start; because the notation here is hexagonal rather than standard algebraic, an edited entry that the replayer cannot interpret — and every entry after it — is struck through as unreachable, and the board shows the last position actually reached. Playing by pointer, rather than by editing the list, is the reliable way to reach a position in this version. A game whose move list has been edited is not saved across a page reload.