Morris

Seven mill-formation variants on concentric-ring graph boards, with placement and movement phases, and the same embed and SDK every family uses.

Embed via iframe

Every game family shares one embed surface. Select the family and variant through the URL.

<iframe
  src="https://engine.moddable.games/play/?embed=1&family=morris&variant=nine-mens-morris"
  style="width:100%;max-width:560px;aspect-ratio:1/1;border:none"
  title="Play Morris"
></iframe>

URL parameters

Param	Values	Default
`embed`	`1`	Required for embed mode
`family`	`morris`	`chess`
`variant`	Any variant key below	`nine-mens-morris`
`opponent`	`ai` \| `human`	`ai`
`difficulty`	`beginner` \| `easy` \| `medium` \| `hard` \| `expert`	`medium`
`theme`	Board theme id	`classic`

postMessage control

Commands accept either the generic game: prefix or the family prefix, so game:undo and morris:undo both work.

iframe.contentWindow.postMessage({ type: 'game:setVariant', variant: 'lasker-morris' }, '*')
iframe.contentWindow.postMessage({ type: 'game:setDifficulty', difficulty: 'hard' }, '*')
iframe.contentWindow.postMessage({ type: 'game:newGame' }, '*')
iframe.contentWindow.postMessage({ type: 'game:undo' }, '*')
iframe.contentWindow.postMessage({ type: 'game:resign' }, '*')
iframe.contentWindow.postMessage({ type: 'game:requestState' }, '*')

Events from embed

window.addEventListener('message', (e) => {
  switch (e.data.type) {
    case 'game:ready':  break  // { family, variant, state }
    case 'game:move':   break  // { move, state }
    case 'game:status': break  // { text, gameOver, family, variant }
    case 'game:state':  break  // { state } in reply to requestState
  }
})

Variants

All seven variants from the moddable-rules Morris hub are playable. Each is fully declared in frontmatter; the plugin holds no variant-specific code.

Key	Board	Distinguishing rule
`nine-mens-morris`	3 concentric squares	9 pieces each; place then move; mill removes one opponent piece
`six-mens-morris`	2 concentric squares	6 pieces each; no placement phase (start on board)
`three-mens-morris`	1 square + centre	3 pieces each; tic-tac-toe on a graph; first mill wins
`twelve-mens-morris`	4 concentric squares	12 pieces each; diagonals on the outer ring
`lasker-morris`	3 concentric squares	10 pieces each; may hop over an adjacent man
`morabaraba`	3 concentric squares	South African variant; diagonal connections
`shax`	3 concentric squares	12 pieces each; Somali variant

Mechanics

The plugin handles placement, movement, mill detection, and removal. All configuration arrives via frontmatter:

Config key	Effect
`piecesPerPlayer`	How many men each player places (3, 6, 9, 10, or 12)
`allowHop`	Whether a man may hop over an adjacent man (Lasker)
`diagonals`	Whether diagonal edges exist on the graph
`flyingWhenThree`	A player reduced to 3 men may move to any empty node

The game has two phases: placement (alternating until all men are down) and movement (slide along edges). Forming a mill (three in a row along an edge) lets the player remove one opponent piece. A player with fewer than 3 pieces or no legal moves loses.

SDK

import { createGame, createAI, listVariants } from 'moddable-engine/play'

listVariants('morris')                        // [{ key, label, group, board }]
const game = createGame('morris', 'nine-mens-morris')
game.applyMove({ action: 'place', to: 'n1' })

const ai = createAI('morris', 'nine-mens-morris', { difficulty: 'hard' })
ai.pickMove(game.getState().slice, 0)         // minimax with mill evaluation