Skip to main content

Documentation Index

Fetch the complete documentation index at: https://openturn.io/docs/llms.txt

Use this file to discover all available pages before exploring further.

Openturn is currently in an early alpha stage. APIs may change quickly, behavior may shift between releases, and the platform should be expected to be unstable while the core framework and hosted services are still evolving.
Openturn lets you write a turn-based game once in TypeScript and run it anywhere turns make sense: on a single device, in a local dev stack, or as a cloud-hosted multiplayer service. You describe the game as a plain value (state, moves, who can act, what each player sees); openturn handles the rest — running the rules, validating moves, syncing players, recording replays. A 30-second taste: 
import { defineGame, move } from "@openturn/gamekit";

export const game = defineGame({
  maxPlayers: 2,
  setup: () => ({ value: 0 }),
  moves: {
    increment: move({
      run({ G, move, player }) {
        const value = G.value + 1;
        if (value >= 5) return move.finish({ winner: player.id }, { value });
        return move.endTurn({ value });
      },
    }),
  },
  views: {
    public: ({ G, turn }) => ({ value: G.value, currentPlayer: turn.currentPlayer }),
  },
});
That single value drives a local React app, a CLI, a hosted multiplayer server, an inspector, and replays — no extra wiring per surface.

​
What you get

  • A game is a plain value. You declare a state, a roster, moves, and views. The engine runs them. Nothing is hidden inside the framework — no globals, no implicit side effects.
  • One definition, every surface. The same defineGame(...) value powers a local React app, a CLI, a hosted multiplayer server, and a cloud deployment. Switching surfaces does not require touching the game.
  • Two authoring layers. @openturn/gamekit is the shortcut: declare phases, moves, turn policy, and outcomes. @openturn/core is the lower level — events, states, and transitions — for when you need full control of the state graph.
  • Deterministic replay and inspection. Every match produces a JSON log. Re-dispatch it and you get the exact same state, every time. The inspector lets you scrub through frames.
  • First-class hidden information. views.public and views.player decide what each audience sees, at the engine level — opponents never receive secrets they should not see.
  • Plug-and-play AI bots. Write a decide function (random, heuristic, or MCTS) and drop it into any seat. The same bot runs locally and over the network.

​
When to reach for openturn

  • You are building a turn-based, round-based, or phase-based game (chess, poker, deckbuilders, negotiation, tactics, party).
  • You want server-authoritative rules and clients that never receive secrets.
  • You want replays, undo, and a debug inspector without building them yourself.
  • You prefer plain TypeScript definitions over config files or a DSL.

​
When something else might fit better

  • Real-time action games (shooters, racers) where state ticks every frame.
  • Games dominated by physics or continuous simulation rather than discrete moves.
  • Non-game workflows that happen to be turn-shaped — a task queue or generic state machine library has less surface area.

​
Where to go from here

If you have never seen openturn before, follow these in order:
  1. Install and run the examples — five minutes, just to see what the running games look like.
  2. Your first game — scaffold a project with openturn create and edit your way to a playable React game in ten minutes.
  3. Tic-tac-toe with gamekit — the full guided tour: a real game, a React UI, and an optional CLI. Subsequent tutorials reuse it for hosted multiplayer, replays, raw core authoring, and bots.
Prefer the mental model before the hands-on tour? Start with concepts: mental model. Want to see a fully realized openturn game? The Splendor example is the flagship — 2–4 player hosted multiplayer with hidden per-player state, three difficulty-tiered AI bots in the lobby, and a polished tabletop UI. Run it with bun --filter @openturn/example-splendor-app dev.