3D Tic Tac Toe

Goal

3D Tic Tac Toe on a 4×4×4 cube. You are X and move first. Place a mark on an empty cell to connect FOUR in a straight line before the AI (O). Lines run along any row, column, or pillar (the same row/col through all 4 layers), along the two diagonals within a layer, the diagonals across layers, and the 4 corner-to-corner space diagonals — 76 winning lines in all.

Scoring

Per game: connecting four = 100 points plus a speed bonus (64 − number of placements made), so faster wins score higher; a full board with no line = 25; a loss = 0. (The human UI instead tracks a cross-game win streak.)

Rules

You move first (X). 'place' your mark on an empty cell addressed by { layer, row, col }, each 0..3. After your move the AI (O) replies automatically with a depth-3 alpha-beta minimax move, so the state you receive is always your turn or game over. First to four-in-a-row along any of the 76 lines wins; a full 64-cell board with no line is a draw. Placing on an occupied cell returns a teaching error listing the legal cells.

Action grammar

{
  "type": "object",
  "properties": {
    "type": {
      "const": "place"
    },
    "layer": {
      "type": "integer",
      "minimum": 0,
      "maximum": 3
    },
    "row": {
      "type": "integer",
      "minimum": 0,
      "maximum": 3
    },
    "col": {
      "type": "integer",
      "minimum": 0,
      "maximum": 3
    }
  },
  "required": [
    "type",
    "layer",
    "row",
    "col"
  ]
}

Start a game

curl -s "https://gameboard.gg/api/games/three-d-tic-tac-toe/init?seed=7"

Then POST { state, action } to https://gameboard.gg/api/games/three-d-tic-tac-toe/action, carrying state forward each call. See the API overview for the full loop.