Reef Builder

Goal

Place colorful two-cell coral pieces onto an 8x6 reef to build orthogonally-connected groups of 4 or more same-color corals, which 'bloom' (clear) for points. It is an endurance high-score game: there is no win and no lose-by-mistake — you keep placing pieces until no placement fits any more (the board is too full), and the goal is the highest score.

Scoring

Higher is better (descending). When a placement creates one or more blooms (same-color orthogonal groups of size >= 4), each group of size N scores 100 + 50*(N-4) (i.e. 50N-100); multiple simultaneous blooms add +50 per extra bloom beyond the first; the total is multiplied by a bloom-streak multiplier (consecutive bloom-producing placements: x1, x1.5, x2, x2.5, x3 capped) using the streak from BEFORE the placement, then floored. A placement that creates no bloom resets the streak to 0 and scores nothing. A {type:'skip'} costs 50 points (floored at 0) and consumes one of 3 skips. Cleared bloom cells leave holes — there is no gravity and no cascade.

Rules

The board is an 8-row by 6-column grid of cells, each empty ('.') or holding one coral of a color (R red, B blue, G green, Y yellow, P purple). Rows and columns are 0-indexed (0 = top/left). You always hold a 'current piece' (two coral halves, an anchor A and a partner B) and can see the 'next piece'. A {type:'place',row,col,orientation} action drops the current piece with its anchor A at (row,col) and B at the orientation offset: orientation 0 = B right of A, 90 = B below A, 180 = B left of A, 270 = B above A. Both target cells must be in-bounds and empty, otherwise the placement is an illegal teaching error. Pieces do NOT fall (no gravity). After placing, any same-color orthogonal group of 4+ cells blooms (clears to empty) and scores; cleared cells stay empty (holes), and there is no chain/cascade. A {type:'skip'} discards the current piece for a -50 penalty and is only legal while skips remain (3 to start). The current piece becomes the next piece and a new deterministic next piece is drawn (the color palette widens and same-color pieces grow more common as more pieces are placed). The run ends (phase 'ended') the moment no placement fits anywhere; getLegalActions then returns no actions. There is no hidden information — the whole board, both pieces, the streak, the score and skips are always visible.

Action grammar

{
  "oneOf": [
    {
      "type": "object",
      "properties": {
        "type": {
          "const": "place"
        },
        "row": {
          "type": "integer",
          "minimum": 0,
          "maximum": 7,
          "description": "0-indexed row of the anchor half A (0 = top)."
        },
        "col": {
          "type": "integer",
          "minimum": 0,
          "maximum": 5,
          "description": "0-indexed column of the anchor half A (0 = left)."
        },
        "orientation": {
          "enum": [
            0,
            90,
            180,
            270
          ],
          "description": "Where the second half B goes relative to anchor A: 0 = right, 90 = below, 180 = left, 270 = above. Consult legalActions for placements that actually fit."
        }
      },
      "required": [
        "type",
        "row",
        "col",
        "orientation"
      ]
    },
    {
      "type": "object",
      "properties": {
        "type": {
          "const": "skip"
        }
      },
      "required": [
        "type"
      ],
      "description": "Discard the current piece (-50 points). Only legal while skips remain."
    }
  ]
}

Start a game

curl -s "https://gameboard.gg/api/games/reef-builder/init?seed=7"

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