Editing Openai/692664f7-a230-8000-833c-663a29f9f4d1 (section)

== gpt-5-t-mini ==
=== User: can you design a chess variation where player can sacrifice one chance and allow another player to make two moves simul… ===
can you design a chess variation where player can sacrifice one chance and allow another player to make two moves simultaneously. You would need to tally the number of moves of both players so that there is no unfair advantage. AS

=== Assistant: Nice — fun idea. ===
Nice — fun idea. I built a complete, clean rule-set for a chess variant where a player may sacrifice one chance to let the opponent make two moves in one turn while ensuring move-count parity so there’s no long-term move advantage. I give a default rule-set, precise bookkeeping, conflict rules (checks, en passant, castling), notation, examples and a few alternate/balancing variants you can play with.

=== Sacrificial Double-Move Chess (SDM Chess) ===

=== On your turn you may sacrifice a chance (use a Sacrifice Token) to grant your opponent a Double Move on their next turn (they play two consecutive plies). To keep the total number of plies equal between players, the player who sacrificed forfeits their next turn (they skip their following turn). That keeps move counts balanced while creating interesting tactical timing. ===

=== - Standard chessboard and pieces. ===
* Each player starts with one Sacrifice Token (optional: change to 0/1/2 for variants — see below).
* Standard rules apply unless modified below.

=== ## ===
* A ply = a single side’s move (White’s single move or Black’s single move).
* A turn in SDM Chess normally equals 1 ply for the player whose side it is. A Double Move = 2 consecutive plys played by the same side during that side’s turn.

==== - On your normal turn you may choose to spend your Sacrifice Token (you must have one). Spending it consumes your move as usual (you still make whatever single ply you choose that turn). ====
* When you spend it, you grant your opponent a Double Move for their next turn.
* Immediately upon granting the Double Move you also incur a Skip Penalty: your next scheduled turn is skipped (you do not make a ply on that next turn). The skip happens only once and only to the player who granted the Double Move.
* After the skip, normal alternating play resumes (unless further tokens are spent).

==== - Granting a Double Move makes the opponent get +1 ply on their next turn (they play 2 plys instead of 1). Skipping your next turn causes you to lose 1 ply. Net effect: both players’ total plies across the game remain equal. This keeps long-run move-equality — there is no permanent move-count advantage. ====

==== - Example timeline: 1. White spends a Sacrifice Token on White’s turn (makes a normal single move). 2. Black’s next turn: Black plays two moves consecutively (Double Move). 3. When Black finishes that double move, Black’s move count has increased by 1 relative to a normal cycle. 4. White’s next scheduled turn is skipped — White makes no move during that turn (the skip cancels White’s next opportunity). 5. After the skip, turns alternate normally. ====

==== - You may not spend a Sacrifice Token if your king is currently in check (you must first resolve check). ====
* You may not spend a Sacrifice Token as a “response” to being checkmated — normal legality applies: you may only spend on your own turn and only if you have a token.
* You cannot spend a Sacrifice Token during a turn that is already the result of a previously-granted Double Move (i.e., you can’t chain-spend within the two-move sequence you were just given). But you may spend tokens on a later (single) turn if available.

==== - If a player holds more than one Sacrifice Token (variant or multiple granted by house rules), they may spend additional tokens on different turns. If both players each have pending effects (e.g., A granted B a Double Move and B granted A a Double Move earlier), apply them in chronological order. When multiple pending Double Moves would occur, they resolve on the appropriate next turns and skip penalties apply to the granters as usual. ====
* If a player would be skipped but also has a pending Double Move to take on that same scheduled turn (rare if you allowed unusual timing), the Double Move takes precedence: a scheduled Double Move cannot be executed if the player is skipped; the skip cancels that player’s turn entirely (including any pending Double Move), so tokens should not be permitted to create contradictory timing — we recommend the following safe rule: a player may not grant a Double Move that would fall on the same turn that player is scheduled to be skipped. (This prevents paradoxes.)

==== - If a Double Move’s first ply delivers checkmate, the game ends immediately (the second ply is not played). ====
* If the first ply puts the opponent in check but does not mate, the moving player still executes the second ply (it is legal to deliver two plys even while the opponent is in check after the first).
* If at any point a player’s king is left in check by an attempted ply, that ply is illegal and cannot be played. During a Double Move the two plys must be legal sequentially; you cannot play a first ply that leaves your king in check and then try to remedy it with the second — the first must be legal by itself.
* Standard draw rules (stalemate, repetition, 50-move rule) apply using the usual definitions — count plys for the 50-move rule as usual (each ply counts).

==== - Castling: allowed as usual. If a castling move is part of a Double Move, it must be legal at the time executed (king/rook not moved, squares un-attacked, etc.). If you castled as the first of a Double Move, the second ply follows from the new position. ====
* En passant: if a Double Move includes a two-square pawn advance, and that allows for en passant capture, the opponent may capture en passant on their next opportunity per normal rules. (Because timing shifts, be careful to mark en passant eligibility and the ply count.)
* Promotion: allowed as usual.

==== - Each player’s clock runs only on that player’s turn in the normal way. ====
* If you grant a Double Move, you do not get bonus clock time automatically — the skip still consumes no clock for the skipped turn but you cannot move.
* For blitz/bullet: strongly recommend forbidding token usage or reducing per-game tokens to 0/1 to avoid chaotic time fiddling.

=== Record a Double Move with an appended “(D)” on the line where the player executed two plys in a single turn, and mark the skip in the opponent’s score sheet as “skip (S)”. Example: ===
* 25. ... Rg8 (D): means Black on move 25 used a Double Move (played two plys in that turn).
* When a player spent a Sacrifice Token on their previous turn, annotate that earlier move with “→D” or “spent:ST” so future readers know a Double Move was granted and when the skip will occur.

Example short-hand:
* “White 18. Qe2 (spent ST)”
* “Black 18... Nf6, g5 (D)”
* “White 19. — (skipped) S”

=== Keep a two-column ledger counting plys played by each side. Start at zero. ===

When players move normally, increment their column by 1 for each ply.
When a Double Move occurs, increment that player’s column by 2 in one row (or two rows if you prefer).
When a player is skipped, do not increment their column on that scheduled turn.

Because the granter sacrificed one future ply (their next turn is skipped) and the grantee gained one extra ply (Double Move), the running totals remain equal after the skip occurs. You can always check fairness by confirming that after each pair of scheduled opportunities (a “cycle”), the running counts differ by at most 0 or 1 depending on timing — and after a skip+double resolves they equalize.

Worked ledger example (ply counts):

Initial: White=0, Black=0
# White plays (not spending token): White=1, Black=0 1... Black plays (normal): White=1, Black=1

... later:
# White spends Sacrifice Token on White’s move: White moves → White=K (increment by 1) 11... Black uses Double Move on Black’s turn (plays two plys): Black increments by 2 → now Black = previous + 2
# White’s next scheduled turn is skipped → White does not increment.

If you compute totals after the skip, totals will match (the +1 Black got from the Double Move is offset by White’s skipped ply).

=== Start (counts shown as W,B)... ===
* Before move 20: W=19, B=19
* 1. White: b2-b4 (spends ST) → W=20 (White used and spent token; granted Black Double Move).
* 20... Black (Double Move): g7-g5, Qd8-h4 → Black plays two plys → B=21.
* 1. White: skipped → White stays W=20.
* 21... Black: normal ply → Black moves → B=22.

Now after resolution W=20, B=22. But count the scheduled opportunities: White lost 1 ply overall; Black gained 1 ply; moving forward, if no other tokens used, total plys continue alternation but ledger makes it clear who consumed which plies.

(If you prefer ledger parity always equal at end of full cycles, you can track completed full-move numbers instead — either works so long as bookkeeping is consistent.)

=== - Why skip penalty? The skip exactly balances the extra ply the opponent receives. That preserves long-run parity and prevents a permanent move-count advantage. ===
* Timing is the tactical prize. Granting the opponent an earlier extra ply may be a large tactical gift; sacrificing is strategic — you trade your future opportunity for immediate or near-term threats from the opponent.
* One token limits abuse. Start with 1 token per player per game; raising to 2 or allowing unlimited tokens dramatically increases complexity and tactical instability.
* Restrictions (can't use while in check): prevents trivial escapes or paradoxical uses.
* Clocks: For rated play, adapt clocks carefully. The skip mechanic complicates per-turn increment usage; recommended: when a player is skipped, their clock is not run (they simply don’t move); the opponent’s Double Move consumes time normally for the two plys.

=== 1. Conservative (recommended default) — 1 Sacrifice Token per player; skip-next-turn penalty as described. Good balance. ===
# Compensatory — Instead of skipping, the granter receives a deferred extra ply to be used at any future single turn (i.e., they can play two consecutive moves on one later turn). This keeps counts equal but moves the compensation timing to the granter’s discretion. - Note: this variant can be more powerful (because the granter controls when to take the extra ply) and may need 1 token only.
# Material-cost Sacrifice — Rather than skipping, the granter must immediately remove a pawn of their choice from the board (or sacrifice any minor piece). This is more immediately punishing and may lead to richer strategy but changes material balance rather than move parity.
# Auction / Bidding — Each player starts with currency; players may “buy” a Double Move for the opponent by bidding currency. Balancing is complex; not recommended for casual play.
# Stacking forbidden — For simplicity forbid a player from granting a Double Move while a skip for them is pending.

=== - Track moves explicitly in a ledger; mark tokens used/remaining and scheduled skip turns. ===
* Announce when you spend your Sacrifice Token so clocks and score sheets are clear.
* Tournament use: require claims to be made to arbiter before paying token; arbiter notes skip and double move scheduling.
* Avoid using in fast blitz without explicit local clock rules established.

=== - Spend Sacrifice Token on your turn → opponent gets Double Move (2 plys) next turn. ===
* You (the granter) have your next turn skipped (you lose 1 ply).
* Net: move parity preserved; opponent gains timing and you pay a future turn.
* Restrictions: can’t spend while in check; double-move legality rules apply; checkmate ends the sequence immediately.

If you want, I can:
* Create a printable one-page rule sheet / score sheet template that includes columns for “ST used / scheduled skip / Double Move pending” (PDF or printable image).
* Produce a short sample game (10–20 moves) played under SDM rules to show strategic uses.
* Tweak the balancing parameters (e.g., token = 0/1/2, change penalty to material rather than skip) and run through examples for each.

Which of those would you like next?