Chess Is a Joke — Variant Rules

1) Board & Setup

• Board: 9 files × 9 ranks.
• Pieces: Standard set plus one Joker per side.
• Suggested back rank (White, left→right): R N B Q K B J N R. Black mirrors.
  Note: Other initial Joker positions are possible; mechanics below are independent of exact Joker slot.
• Pawns: Start on White’s rank 2 / Black’s rank 8; move upward/downward as usual (with 2-step option from the start square).

2) The Joker (new piece)

2.1 Core mechanic — Freezing

• The Joker cannot capture and exists only to freeze enemies.
• Whenever a Joker ends a move adjacent (orthogonal or diagonal; the 8 surrounding squares) to one or more enemy pieces, it freezes the highest-value one among those adjacent targets.
• King and opponent Joker are not a valid freeze targets.
• Ties: If two or more adjacent enemies share the same highest value (e.g., two bishops), all tied highest pieces become frozen.
• Retargeting: If a higher-value enemy subsequently becomes adjacent while the Joker remains, the freeze retargets to that higher-value piece; previously frozen lower-value pieces immediately unfreeze.

2.2 Freeze effects

• A frozen piece cannot move or capture and is treated as exerting no attack/control over squares while frozen.
• Because frozen pieces do not give check, a king may legally move into or through squares “controlled” only by frozen enemies.
• Persistence:
  • If the Joker moves away, the last frozen piece remains frozen for exactly one additional friendly turn and then unfreezes.
  • If the Joker is captured, all pieces it had frozen unfreeze immediately.

2.3 Movement

• The Joker moves as a knight (an L-shaped jump: two squares in one direction, one perpendicular), may leap over pieces, must land on an empty square, and cannot capture. (Variants are possible without changing the invention; the freeze mechanic is independent of the exact movement pattern.) The freezing rules above apply regardless of the movement pattern.

3) En Croissant (pawn special)

En Croissant is a freeze-based response available when enemy pawns advance in adjacent files.

3.1 Preconditions (strict mode)

• Two opposing pawns occupy adjacent files.
• Both pawns must have used their initial two-square advance earlier in the game (their respective first pawn moves).
• Later, when one pawn advances a single square so that the two pawns become side-by-side on the same rank (i.e., the passer “tries to sneak by”), the other side gains a one-move option.

3.2 The En Croissant move

• On the very next move only, the non-moving side may move its pawn diagonally into the file of the passer, to the square directly behind that pawn (relative to the passer’s travel direction).
• No capture occurs. Instead, the passed pawn becomes frozen for its next turn only. After that one turn, it unfreezes automatically.
• If not exercised immediately, the En Croissant right expires.

4) Other rules & clarifications

• Promotion: A pawn that reaches the back rank may promote to Q, R, B, N, or Joker (not to King).
• Castling: Allowed with standard conditions (king/rook unmoved, clear path, king not in/through/into check). On a 9×9 board, final squares may be adjusted by implementation; the common choice places the king one square from the edge on the castling side.
• Check / Checkmate / Stalemate: Attacks by frozen pieces are ignored. Checkmate and stalemate are evaluated using only unfrozen attacking lines.
• Scoring (optional): Capturing a Joker is worth 0 points and does not reset a 50-move counter.

5) Definitions

• Adjacent: Any of the 8 squares immediately surrounding a piece (orthogonal or diagonal).
• Behind (for En Croissant): The square directly on the passer’s file, one rank opposite its movement direction from the side-by-side position.

6) Example situations (text)