Hidden960 Prototype with Unreveal, Castling, Undo & Reset

Current Turn: White
Hidden960 Chess Variant – Rules

Hidden960 Chess Variant – Rules

  1. Starting Position & Setup
    1. Back Rank (Unrevealed):
      • Each player’s back rank (White’s 1st rank and Black’s 8th rank) starts entirely hidden (gray squares).
      • Each player has a pool of pieces: 1 King, 1 Queen, 2 Rooks, 2 Bishops, and 2 Knights. These pieces will eventually be placed on the hidden squares as they are revealed.
      • The order is not predetermined; you choose the piece for each square when revealing it.
    2. Pawns:
      • White’s pawns are placed on rank 2 and Black’s on rank 7, and they are visible from the start.
  2. Revealing Pieces
    1. On your turn, you may reveal one or more hidden squares on your back rank by selecting a gray square.
    2. When you reveal a square, you choose one piece from your available pool to assign to that square.
    3. Revealing a piece does not count as your move.
    4. Once revealed, a piece’s identity is fixed and cannot be unrevealed.
  3. Forced Reveals
    1. If an unrevealed square is threatened by an opponent’s piece, that square must be revealed immediately.
    2. If your move causes an unrevealed square to become threatened, you must reveal that square immediately.
  4. Revealing the Final Hidden Squares
    1. When only two hidden squares remain on your back rank, you must reveal them together on the same turn.
    2. This rule prevents leaving a lone unrevealed square that might create ambiguity with the forced-reveal rules.
  5. Movement & Turn Order
    1. After revealing (if necessary), you make your move following standard chess rules.
    2. Only an actual move (or castling) counts as your move; revealing does not consume your move.
    3. Turn progression continues normally after your move is complete.
  6. Castling (Chess960-Style)
    1. Standard Chess960 castling rules apply with these additional conditions:
      1. Neither the king nor the involved rook may have moved previously.
      2. Revealing a piece does not count as “moving” it; only an actual move or castling forfeits castling rights.
      3. The final landing squares for castling must be already revealed and empty:
        • For kingside castling: the king must land on file 7 and the rook on file 6.
        • For queenside castling: the king must land on file 3 and the rook on file 4.
      4. All squares between the king and the eligible rook must be revealed.
    2. If any of these conditions are not met, castling is not allowed.
  7. Standard Chess Rules
    1. All standard chess rules regarding legal moves, check, checkmate, stalemate, etc., apply.
  8. Strategic Considerations
    1. The variant is designed to limit computer analysis and emphasize human intuition by introducing hidden information.
    2. Forced reveals ensure that if a hidden square becomes critical, its contents become known.
    3. Revealing the final squares together prevents ambiguity.