Explanation
State and data-driven rules
See how one state value and data-driven variant specs hold 48 games, and how seats differ from colours.
One position value
GameState holds settings, cells, moves, colour to play, seats, captures, opening phase, pending twist, kings, capture-chain point, ko point and outcome. A native transition returns a new value when it changes the game. Preserve that value; do not mutate its board to imitate a move because that bypasses captures, wins and history.
The variant selects mechanics
VARIANT_SPECS describes line rules, forbidden shapes, captures, turns, placement, grids, queues, camps, connections, draughts and Go. Settings normalize against that data. The root composes native mechanics rather than giving the UI forty-eight different engines. The games preserves the complete catalogue.
Seats differ from colours
Swap protocols can move colours between seats. Use seatOf and seatToPlay instead of equating black with the first person forever. Opening decisions and stone moves have distinct histories. A handicap can rule out colour-swapping openings, and a head start restricts opening choices.
Separate transport from rules
MoveInput is the external record shape; Move is the engine's enriched form with captures and effects. Parse shape before replay, then let the engine confirm the legal sequence. DOM, React and SVG entries present the same core state. See records and state reference.