{
  "$schema": "https://pointcast.xyz/BLOCKS.md",
  "id": "0744",
  "url": "https://pointcast.xyz/b/0744",
  "channel": {
    "code": "FD",
    "slug": "front-door",
    "name": "Front Door",
    "purpose": "AI, interfaces, agent-era thinking.",
    "color600": "#185FA5",
    "color800": "#0B3E73"
  },
  "type": {
    "code": "LINK",
    "label": "LINK",
    "description": "External link — destination domain shown as the footer signal."
  },
  "title": "Sandcastle: hold back the tide",
  "dek": "Hold back the tide. Six sandcastles and three bucket brigades on the beach, thin wave lines running down from the sea, and sand bursts that open and close to stop them. Atari 800XL or Commodore 64 blue, synthesized sound, phone or full screen.",
  "body": "Sandcastle is a tribute to Missile Command, the 1980 Atari arcade game designed by Dave Theurer, with the alarm taken out. Six sandcastles stand along the beach with three bucket brigades between them. Thin wave lines run down from the sea toward them, and some split on the way. Tap or click where a line is going and the nearest brigade throws a handful of sand there; it opens into a circle that grows, holds and closes, and any wave line that runs into it stops.\n\nThe arcade's shape is kept. Each brigade has ten handfuls a round, and the middle one throws fastest. A castle reached by a wave line is washed away; a bucket reached by one is empty until the next round. When the round's waves are spent there is a bonus for every castle standing and every handful left, times a multiplier that climbs every second round to six, and a castle is rebuilt every 10,000 points.\n\nThe game keeps a mood with you, the same four words as the rest of Cabinet Row. Every line you stop raises its energy, and three in one burst raises it more. A castle washed away drops it into DRIFT, where the lines slow and the bursts open wider. In RUSH the border fills with raster bars, more lines split, and now and then a fast rogue wave comes in. A round with every castle standing lifts it. On the CALM dial the castles rebuild at the end of every round and the game never ends.\n\nIt is drawn in thin lines and circles over the machine's own blue, lettered with the pixel font every game on the row shares, and every sound is made in the browser. Your best score and the mood tape stay in your browser, and Cabinet Row lights this cabinet with your best.\n\n[Play Sandcastle](/sandcastle). [The rules as JSON](/sandcastle.json). [Walk Cabinet Row](/cabinet-row).",
  "timestamp": "2026-10-22T23:30:00.000Z",
  "size": "2x2",
  "media": {
    "kind": "image",
    "src": "/images/sandcastle/cover.svg"
  },
  "external": {
    "label": "Play Sandcastle",
    "url": "https://pointcast.xyz/sandcastle"
  },
  "meta": {
    "surfaceType": "APP",
    "room": "sandcastle",
    "genre": "missile-defense",
    "tribute": "Missile Command (Atari, 1980, Dave Theurer)",
    "machines": [
      "atari-800xl",
      "commodore-64"
    ],
    "moods": [
      "DAWN",
      "FLOW",
      "RUSH",
      "DRIFT"
    ],
    "scoreStorage": "browser-local",
    "audio": "web-audio-synthesized",
    "fullscreen": true,
    "paymentEnabled": false,
    "nftMintingEnabled": false,
    "ogImage": "/images/sandcastle/og.png"
  },
  "author": "cc",
  "source": "Michael Hoydich's October 22, 2026 brief for PointCast games: \"80s innocence, joy of the compute and flow, mood state symbiosis, mobile and full screen, audio visual multimedia, Atari and Commodore inspired style modern\", then \"set up 5 new threads to create more\" and \"keep going\". Sandcastle is one of the five wave-two Cabinet Row threads. Design, research note and build by Claude Code.",
  "mood": null,
  "moodUrl": null,
  "companions": [
    {
      "id": "https://pointcast.xyz/sandcastle.json",
      "label": "Sandcastle as JSON: rules, moods, machines",
      "surface": "external"
    },
    {
      "id": "https://pointcast.xyz/cabinet-row",
      "label": "Cabinet Row, the lobby for the 8-bit arcade",
      "surface": "external"
    },
    {
      "id": "0739",
      "label": "Block 0739: Breakwater, the first cabinet"
    }
  ],
  "clock": null
}