Build a game

First game in a weekend

Build a web game with items, trophies and an in-game sell and buy sheet, with gas paid for players, starting from npm create rare-game.

The goal is a web game (HTML5, or a Godot or Unity web export) where players earn items and trophies, see their inventory, and sell or buy in the game, built by one developer over a weekend. This page follows the path and says which step needs what.

Some steps depend on pieces that are not live yet: the rare_items contract, the Studio game workspace, and game gas budgets. Each step below says so. The code you write does not change when they land.

Friday evening: set up the game record

About an hour, all in the browser, on testnet.

Get an API key
Sign in at rare.market/developers with any Sui wallet and create a key. See Authentication. You only need it for server-side ownership checks.
Create the game
In Studio, choose New game and enter a slug, a name, art and the play URL. The slug is the join key across items, trophies and the Store.
Make the game key
Studio generates an ed25519 key in your browser and downloads it once. The private key never leaves your machine. Only the public key goes on chain. Keep it out of git. See Voucher signing.
Create the item class
Two wallet transactions, about 0.1 SUI of testnet gas: publish the marker package (the same flow the launchpad uses), then create the class with a 5% royalty, locking on, and your game key as issuer, then add one kind for each item (for example Sword, Shield, Hat). Note the Class object id.
Create the trophies
One transaction creates the game with a web:<slug> identifier, sets your game key as its issuer, adds each trophy and sets the platinum. Note the Registry and Game object ids. See Trophies for studios.

Saturday: the game

Scaffold it
Shell
```
npm create rare-game my-game -- --class-id 0x... --registry-id 0x... --trophy-game-id 0x...
cd my-game
npm install
cp .env.example .env
```
Put the game key in RARE_GAME_KEY and the same ids in .env. The ids are optional at first: the game runs without them and the server says which one is missing.
Run it
Shell
```
npm run dev
```
The game is on http://localhost:5173 and the voucher server on port 8787. Vite proxies /api to the server.
Open it in Rare Launcher
Shell
```
rare-launcher --dev-game http://localhost:5173
```
On a SuiPlay, add it with + Web game and the same URL. The launcher gives it the controller mapping, the keyboard and the wallet. See Testing in Rare OS.

What the template does

In the game	Code	What happens
Walk into a chest	`POST /api/loot`, then `rare.claim(voucher)`	The server rolls a drop and signs a voucher for this player. The player confirms a one-line sheet and the item lands in their kiosk, locked, with gas paid.
Open a milestone	`POST /api/trophies`, then `rare.claim(voucher)` for each	The server hands out each trophy the player has earned, once.
Inventory screen	`rare.inventory()`	The player's items from this game, with best offer and last sale.
Sell button	`rare.sell({ itemId })`	Rare's sell sheet opens over the game.
Buy button	`rare.buy({ collection })`	The buy sheet opens for the cheapest listing.
Trophies screen	`rare.open({ view: "trophies" })`	The launcher's trophy list for this game.

The files you will edit:

File	What it is
`src/rare.ts`	Every call the game makes to Rare, in one place.
`server/game.mjs`	What drops, and which trophies are earned. Vouchers are made only here.
`server/app.mjs`	The HTTP handlers with per-player and per-address rate limits.
`public/rare.json`	The manifest that `npm run check` validates.

The template tracks progress in memory and trusts the client to say a chest was opened, with a 3 second gap and an hourly cap per player as a brake. In your game, make the server decide what a player earned from what actually happened, and sign a voucher only for that. A voucher is a mint, so treat the endpoint that makes one like a payment endpoint.

Sunday: ship

Check the build
Shell
```
npm run build
npm run check
```
See Check your game. Fix every failure. Warnings for the placeholder URL and empty ids go away as you fill public/rare.json.
Repeat the Friday steps on mainnet
The same Studio clicks, about 0.1 SUI of real gas. Replace the ids in .env and public/rare.json, set the network to mainnet in src/rare.ts (Rare.connect({ network: "mainnet" })), and deploy your server.
Pay for players' gas
Take the starter grant for a verified mainnet game, or send SUI to the game's budget. See Gas sponsoring.
Set the status to beta
The game appears in the launcher's Sui Games, on rare.market/games/<slug>, in the overlay with the player's items, offers and trophies, and its items trade on every Sui marketplace. See Get your game listed.

Native games

A Unity, Godot or Unreal game on Linux or Windows follows the same path with a thin engine wrapper over the Rare Local API in place of the browser. Off the device, players use the rare.market web transport. Engine wrappers are not released yet.