OSRIC, short for Old School Reference and Index Compilation, is a fantasy role-playing game system and a remake of the 1st edition of Advanced Dungeons & Dragons (AD&D). The present game is a technical remake of Ultima Underworld.

Preview

In this repository, a core common engine is implemented as a fixed stage pipeline to be the core functionality of any kind of turn-based game.

OSRIC-engine uses this engine to be the complete set of commands & rules that implements the OSRIC ruleset.

In the same fashion, a game-independent custom visual engine, a software raycaster, is introduced to be the basis of any kind of First Person Dungeon Crawler game. It does NOT rely on any 2D/3D engine or library.

Rule-Engines & Renderer-Engines are thus meant to be co-located.

Then, Underworld, a technical showcase displaying the raycaster uses OSRIC to create the basis of a "Ultima Underworld"-like game.

Lastly, a distributable is provided as a dektop executable for Linux and a buildable for Windows.

As stated, this is a pnpm workspace with multiple packages:

engine/

• Core simulation runtime and APIs.
• Fixed‐stage pipeline executor, effects buffer, and result types.
• Deterministic RNG with audit trails, integrity hashing, and snapshot diffing.
• Authoring DSL for commands, registry, and facade for clean integration.
• Batch/simulation utilities for scenario building and large‐scale runs.
• ZERO dependencies.

osric-engine/

• Deterministic OSRIC rules on top of the core engine.
• Exposes the DomainEngine facade, domain commands, entities, and scenarios.
• Mirrors certain battle effects into viewer-friendly ones.

renderer-underworld/

• Headless renderer and data structures for a software raycaster.
• Provides textures, palettes, LUTs, sprite helpers, and a simulation loop.
• Creates them when they are not provided.
• ZERO dependencies.

viewer-underworld/

• React based game to visualize the renderer-domain interactions.

distributable-underworld/

• Electron wrapper to ship a desktop version of the viewer-underworld game.

• People building turn-based games who require strong guarantees and clear authoring flows.
• Designers implementing complex rulesets as modular, testable packages.
• People who value good documentation (see Q&A).

import { DomainEngine, DomainMemoryStore } from '@osric/osric-engine';
const store = new DomainMemoryStore();
const engine = new DomainEngine({ seed: 12345, store });
// Execute domain commands by typed key
const res = engine.grantXp('hero-1', 50);
if (res.ok) {
 // effects are mirrored (e.g., battle visuals) and available on success
 console.log(res.effects);
}
// Dry-run safely without inducing store/RNG changes
const sim = engine.simulate('osric:grantXp', { id: 'hero-1', amount: 50 });
console.log(sim.diff);

• See authoring-engine
• See authoring-engine-domain
• See authoring-renderer
• Run the viewer app
  • pnpm -w -F @osric/viewer-underworld dev

MIT License © 2025 Fernando E. Braz