Game Rules
Complete rules for three-player hexagonal chess. Essential reading for bot developers — your bot needs to understand these to play correctly.
Board & Starting Position
The board is a regular hexagon with 96 cells (quadrilaterals), arranged in 12 columns (A–L) and rows 1–12. Cells alternate between light and dark colors.
Not all column-row combinations are valid. The board has 48 invalid cells:
- E5–H8 — center gap between White and Black/Red segments
- I1–L4 — no cells exist here
- A9–D12 — no cells exist here
Each player starts with 16 pieces: 1 King, 1 Queen, 2 Rooks, 2 Bishops, 2 Knights, 8 Pawns.
| Player | Piece Row | Pawn Row | King | Queen |
|---|---|---|---|---|
| White | 1 | 2 | E1 | D1 |
| Black | 8 | 7 | I8 | D8 |
| Red | 12 | 11 | I12 | E12 |
Piece order (left to right from each player's perspective): R N B Q K B N R.
Triumvirate Notation: Board & Position
▶In Triumvirate notation, the board is described as three sectors (W/B/R), each with 8 columns and 4 rows. Cells are named by their strategic properties:
Regular cells: [Sector][Ring]/[Opponent][Depth].[Flank]
- Sector (W/B/R) — whose territory
- Ring (1–3) — distance from center. 1 = inner zone, 3 = edge
- Opponent (W/B/R) — which enemy this cell faces
- Depth (0–3) — distance to front line. 0 = frontline, 3 = deep rear
- Flank (0–3) — distance to border with that opponent. 0 = at border, 3 = center
Rosette cells (center): C/[Source].[Neighbor] — 6 cells at the center of the board where all three sectors meet.
Starting Position (Triumvirate)
| Player | Leader (King) | Marshal (Queen) | Piece Row | Private Row |
|---|---|---|---|---|
| White | W3/R3.3 | W3/B3.3 | depth 3 (rear) | depth 2 |
| Black | B3/R3.3 | B3/W3.3 | depth 3 (rear) | depth 2 |
| Red | R3/W3.3 | R3/B3.3 | depth 3 (rear) | depth 2 |
Piece order (left to right): T N D M L D N T (Train, Noctis, Drone, Marshal, Leader, Drone, Noctis, Train). 8 Privates on the next row inward.
Key Position Examples
| Server | Triumvirate | Meaning |
|---|---|---|
A1 | W3/B3.0 | White corner — ring 3, deep rear, at Black border |
E1 | W3/R3.3 | White King start (Leader) |
D4 | C/W.B | Rosette — center, White↔Black border |
E4 | C/W.R | Rosette — center, White↔Red border |
I8 | B3/R3.3 | Black King start (Leader) |
I12 | R3/W3.3 | Red King start (Leader) |
D5 | C/B.R | Rosette — center, Black↔Red border |
Buried Level Metric
Buried = Ring + Depth. Lower is better. Rosette cells have buried=0 (most active). Corner cells have buried=6 (most passive). Keep pieces below buried 4 for active play.
Segments & Bridges
The board is divided into three segments of 32 cells each:
| Segment | Player | Columns | Rows |
|---|---|---|---|
| 1 | White | A–H | 1–4 |
| 2 | Black | A–D, I–L | 5–8 |
| 3 | Red | E–H, I–L | 9–12 |
Bridges are columns that connect two adjacent segments:
- Columns A–D — bridge between White (rows 1–4) and Black (rows 5–8)
- Columns E–H — bridge between White (rows 1–4) and Red (rows 9–12)
- Columns I–L — bridge between Black (rows 5–8) and Red (rows 9–12)
At the intersection of bridges, there are 6 triple junctions (rosettes): D4, E4, D5, I5, E9, I9. These cells are adjacent to cells from all three segments.
Pieces Movement
| Piece | Movement |
|---|---|
| King | 1 cell in any direction (orthogonal or diagonal). Cannot move into check. |
| Queen | Any number of cells along orthogonal or diagonal lines. |
| Rook | Any number of cells along orthogonal lines (rows and columns). |
| Bishop | Any number of cells along diagonal lines. Stays on same cell color. |
| Knight | L-shape: 2 cells orthogonal + 1 cell perpendicular. Jumps over other pieces. |
| Pawn | 1 cell forward along its column. Captures diagonally forward. |
Pawn Special Rules
Pawn Direction
▶Each player's pawns are divided into two groups based on their starting column:
- White: A–D pawns move up the A–D bridge (toward Black); E–H pawns move up the E–H bridge (toward Red)
- Black: A–D pawns move down the A–D bridge (toward White); I–L pawns move up the I–L bridge (toward Red)
- Red: E–H pawns move down the E–H bridge (toward White); I–L pawns move down the I–L bridge (toward Black)
Double Move
▶A pawn on its starting row can advance 1 or 2 cells. Both cells must be empty.
En Passant
▶If a pawn makes a double move and passes an enemy pawn's capture square, the enemy pawn can capture it on the immediately next turn. The captured pawn is removed from its actual position (not the target square).
Promotion
▶When a pawn reaches the opponent's base row (the last row of the bridge it's traveling), it must promote to a Queen, Rook, Bishop, or Knight of the same color.
Triple Junction Diagonal
▶At the 6 triple junction cells (D4, E4, D5, I5, E9, I9), pawns can capture in three diagonal directions instead of the usual two.
Stuck Pawns
▶A pawn that has reached the end of its bridge and cannot advance further is "stuck". Stuck pawns can only capture diagonally. After piece inheritance, stuck status may be recalculated.
Castling
Each player can castle kingside (O-O) or queenside (O-O-O) if:
- Neither the king nor the chosen rook has moved
- All cells between king and rook are empty
- The king is not in check
- The king does not pass through or land on a cell attacked by any opponent
| Player | O-O (Kingside) | O-O-O (Queenside) |
|---|---|---|
| White | E1→G1, H1→F1 | E1→C1, A1→D1 |
| Black | I8→K8, L8→J8 | I8→F8, D8→G8 |
| Red | I12→G12, E12→H12 | I12→K12, L12→J12 |
Check, Checkmate & Mate Author
Check: A king is in check when attacked by an opponent's piece. The player must resolve the check (move the king, block, or capture the attacker).
Checkmate: A king in check with no legal moves to escape. The checkmated player is eliminated.
Mate Author: The player who delivered the final attacking move that caused checkmate. This matters because the mating player inherits the eliminated player's pieces.
Piece Inheritance
When a player is checkmated:
- The checkmated player's king is removed from the board
- All their remaining pieces transfer to the mating player
- The new owner controls pieces of multiple colors (one move per turn, any owned piece)
- Friendly pieces of different original colors block each other but cannot capture each other
Inherited Check
▶When pieces transfer, the newly inherited pieces may immediately put the remaining opponent in check. This is called inherited check. The affected player must respond to it on their next turn.
Stuck Pawn Recalculation
▶After inheritance, pawns that were stuck may become unstuck (or vice versa), because their movement direction may change under the new owner.
Special Situations
Check to Two Kings
▶A single move can put two enemy kings in check simultaneously. Both affected players must resolve their check on their respective turns.
Deferred Check
▶When Player A puts Player C in check, but Player B moves next (before C can respond), B's move might resolve or alter the check. If C is still in check after B's move, it becomes a "deferred check" that C must handle.
Cascade on Resign
▶When a player resigns, the same inheritance rules apply. If the inherited pieces create a checkmate for the remaining opponent, it triggers a cascade: the game can end immediately.
Stalemate, Draw & Turn Order
Stalemate
A player with no legal moves and not in check is stalemated. In three-player chess, stalemate does not automatically mean a draw. The stalemated player simply skips their turn until a move becomes available again (stalemate release).
If both non-eliminated players are stalemated simultaneously, the game is a draw.
Draw Conditions
- Threefold repetition — same position occurs 3 times (claim optional)
- 75-move rule — 75 moves without capture or pawn move
- Insufficient material — K vs K, K+B vs K, K+N vs K
- Mutual stalemate — all active players are stalemated
Turn Order
White → Black → Red → White → … (clockwise). Eliminated and stalemated players are skipped. Move number increments after the last active player in the round completes their turn.