Building on Aether

The engine is game-agnostic. Every rule you can name lives in content you write.

Aether is a platform, not a game. Nothing in the engine knows what a hit point is. All game meaning lives above it, in packages you build against the stable, semver'd @aether/sdk.

That constraint is the product: implement any ruleset without forking anything, and ship it to every Aether table.

#The three package kinds

Kind	What it is	Ships
`system`	a game's rules, one active per world	document types, sheets, initiative, automation
`module`	content and features on top of a system	content packs (documents, types, sheets, assets)
`mod`	a sandboxed engine extension	iframe code plus capability grants

#A system in miniature

systems/my-system/src/index.tsTypeScript

import type { DocumentSchema } from "@aether/core";
import { defineSystem } from "@aether/sdk";
import { z } from "zod";

const character: DocumentSchema = {
  type: "my.character",
  label: "Character",
  data: z.object({
    str: z.number().int(),
    hp: z.object({ value: z.number().int(), max: z.number().int() }),
  }),
  makeDefault: () => ({ str: 10, hp: { value: 10, max: 10 } }),
  capabilities: ["actor", "effects", "linkable"],
};

export default defineSystem({
  manifest: {
    id: "my-system",
    kind: "system",
    title: "My System",
    version: "0.1.0",
    minSdkVersion: "0.1.0",
    authors: ["you"],
    compatibility: {},
  },
  setup() {
    return {
      documents: [character],
      initiative: "1d20 + ${floor((str - 10) / 2)}",
    };
  },
});

#Two references ship in-tree

systems/demo-system is the minimal reference system.
systems/dnd5e-srd exercises the whole surface: schemas, sheets, active effects, initiative, automation, and a content pack.

#Next

Read The package kinds for how the three fit together, then pick a guide.

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