libd2

Clean-room reimplementation of the Diablo II 1.14d engine core, reverse-engineered from the retail binary with no Blizzard code. Give it a seed and it produces the same world the game does.

npm install libd2

One package for the whole library, one WebAssembly module inside it. No native addon, no build step, no bundler configuration.

import { init, open, Areas, route } from 'libd2';

await init();
using game = open({ seed: 1337 });

// Nothing is generated until an area is asked for; one generation covers its whole act.
const cold = game.area(Areas.ColdPlains);
console.log(`${cold.name}: ${cold.rooms.length} rooms, ${cold.exits.length} ways out`);

// Exits are generated data, so where a level leads is known before you ever stand in it.
for (const exit of cold.exits) console.log(`  -> ${exit.to.name}`);

// Routing crosses levels, so this is one call, not one per area. null means no way through.
const trip = route(game.area(Areas.RogueEncampment).middle, cold.middle, { teleport: true });
for (const leg of trip?.legs ?? []) console.log(`${leg.area.name}: ${leg.moves.length} moves`);

Cold Plains: 97 rooms, 4 ways out
  -> Cave Level 1
  -> Blood Moor
  -> Burial Grounds
  -> Stony Field
Rogue Encampment: 3 moves
Blood Moor: 6 moves
Cold Plains: 5 moves

The same seed always gives the same world, matching the retail engine cell for cell.

What you get

An object model over the generated world, not a JSON dump of it:

• Game — a seed and a difficulty. Generates an act the first time you name an area in it.
• Area — one level: rooms, objects, exits, collision, walk, and at(x, y) for a Location that knows which area it is in.
• route() — walk or teleport between two locations across as many levels as it takes, using the movement rules the server enforces. Also walkableAt, snap, lineOfSight, areasBetween.
• rasterize(), Minimap — turn a level into pixels, or project it the way the game's automap does.

Units can be placed into an area (place, occupy) so routing goes around what is standing there, which is the difference between a path and a path a character can actually walk.

Runs everywhere

The wasm is freestanding and libc-free, so its import object is empty and the same package runs in Node, Bun, Deno and the browser with no polyfills. The shim resolves its wasm relative to its own module URL and feature-detects how to read it.

ESM only, deliberately: Node has been able to require() an ESM graph since 22.12 and the shim has no top-level await, so require('libd2') works without shipping a second build. That is the floor declared in engines.

Is it right?

Map generation is compared cell for cell against dumps captured from the retail engine: 11.1M subtiles per seed, every level of all five acts, zero differing cells, including seeds held back and never looked at during development. See docs/VERIFICATION.md.

Full guide: docs/usage/node.md.

If libd2 is useful to you, you can sponsor the work.

Replaces @jaenster/d2drlg

@jaenster/d2drlg was the previous shape, one package per subsystem wrapping the C ABI directly. It is deprecated in favour of this package.

Licence

MIT. The repository embeds small binary blobs derived from Blizzard game data so the generator builds and self-verifies; they are not redistributable game content. This project is not affiliated with or endorsed by Blizzard Entertainment.