Reference: stages

Stages are sub-steps inside a turn. They let you say things like “first check for forced jumps, then if none exist, switch to a normal move stage”.

Stages live under turn.stages and work together with turn.activePlayers.

Shape

"turn": {
  "activePlayers": { "currentPlayer": "someStage" },
  "stages": {
    "someStage": {
      "initialMoves": [ { "...": "..." } ],
      "moves": {
        "moveName": { "...": "..." }
      }
    },
    "otherStage": { "...": "..." }
  }
}

Each stage can define:

• initialMoves — Array of move rules that run when entering the stage (e.g. to auto-pass, or switch stages if there are no legal moves).
• moves — Map of move names to move definitions that are only available in this stage.

activePlayers maps which players are currently acting to stage names:

• Keys are usually currentPlayer (the player whose turn it is).
• Values are stage names from stages (e.g. "jumpIfPossible", "normalPlay").

Example: forced jumps in Checkers

Checkers uses two stages:

• jumpIfPossible — First stage: if jumps exist, the player must jump.
• moveIfNoJump — Second stage: if no jumps exist, allow normal moves.

"turn": {
  "activePlayers": { "currentPlayer": "jumpIfPossible" },
  "stages": {
    "jumpIfPossible": {
      "initialMoves": [{
        "moveType": "SetActivePlayers",
        "options": {
          "currentPlayer": { "stage": "moveIfNoJump" }
        },
        "conditions": [{ "conditionType": "NoPossibleMoves" }]
      }],
      "moves": {
        "jumpChecker": {
          "moveType": "MoveEntity",
          "arguments": { "...": "..." }
        }
      }
    },
    "moveIfNoJump": {
      "moves": {
        "moveChecker": {
          "moveType": "MoveEntity",
          "arguments": { "...": "..." }
        }
      }
    }
  }
}

Example: normalPlay stage in Eights

Eights has a normalPlay stage used during its play phase:

"turn": {
  "activePlayers": { "currentPlayer": "normalPlay" },
  "stages": {
    "normalPlay": {
      "moves": {
        "playCard": {
          "moveType": "MoveEntity",
          "position": "First",
          "arguments": { "...": "..." }
        }
      }
    }
  }
}

How to use stages

• Model multi-step turns: Use stages when a single turn has distinct steps (e.g. forced capture, bonus move, clean-up).
• Gate moves by stage: Put moves under the stage where they’re legal; a move is only available when its stage is active for that player.
• Transition with initialMoves: Use a stage’s initialMoves to automatically switch stages (e.g. via SetActivePlayers) or to auto-pass when there are no valid moves.

See Turn for how stages fit into the turn config, and how they interact with minMoves, maxMoves, and initialMoves.