Foundry VTT System Development

Build game systems for Foundry Virtual Tabletop (v13+). Systems define the core rules — Actor/Item types, dice mechanics, combat, character sheets — while modules extend them. This skill covers the full system lifecycle from manifest to publication.

Quick Start

System Structure

my-system/
├── system.json           ← manifest (required)
├── template.json         ← type definitions (required)
├── scripts/
│   ├── main.mjs          ← ES module entry point
│   ├── actor.mjs         ← custom Actor class
│   ├── item.mjs          ← custom Item class
│   ├── data/
│   │   ├── character-data.mjs
│   │   └── npc-data.mjs