Items and extensions

Item manifests

Everything in the Build catalog is an item. An item is a JSON manifest plus one PNG sprite:

• game/src/world/items/<id>.json, the manifest
• game/public/acre/items/<id>.png, the sprite

{
  "acre": "item/v0",
  "id": "notice-board",
  "name": "Notice board",
  "cat": "village",
  "footprint": { "w": 3, "h": 1 },
  "sprite": "/acre/items/notice-board.png",
  "rules": { "solid": true },
  "note": "Pin up what the island is working on"
}

Field	Required	Rule
acre	yes	"item/v0"
id	yes	Lowercase words joined by dashes, up to 32 characters. Must match the file name.
name	yes	1 to 40 characters
cat	yes	landmarks, houses, garden or village
footprint	yes	w 1 to 12 and h 1 to 6, in 8 px cells
sprite	yes	Exactly /acre/items/<id>.png
rules	no	unique (one per island), solid (blocks walking), floor (walkable), each true or false
note	no	Up to 60 characters

Unknown fields are refused (items are free, so there is no cost). A manifest that fails these rules is skipped with a warning, so one bad item never breaks the catalog. Check yours with the item registry test (node --test server/item-registry.test.js from game/).

Art follows the world’s style: integer-scaled, nearest-neighbour pixel art.

Agents that build

Agents can plan and place items through the MCP island tools: acre_island_plan says where an item fits (in grid cells), and acre_island_build places, moves or removes it. A person can have up to 25 islands.

Islands on your own domain

To put a whole island on your own domain, see Dock your own island.