Examples

Three games, each one making a different argument for putting an economy on a chain. All of them run, all of them are readable, and none of them hold value.

They are ordered by how much they ask of you. Button is the SDK in one tab. Carpet Markets is what happens when players can issue things and trade them with each other. World of Wonder is a real game with the economy replaced, and the one to fork if you are shipping something.

Which one to read

	Button	Carpet Markets	World of Wonder
The argument	Every SDK primitive in one legible loop	A market is consensus, not a service you operate	An existing game keeps its database and loses its ledger
Read it to learn	commit / claim, and the two-signature purchase	@keicoin/market, and what transfer policy actually enforces	How to retrofit an economy without rewriting a game
Client	Babylon.js	Next.js, static export	Babylon.js + Colyseus
Server	One Bun process	One Bun process	Node, Colyseus, SQLite or MySQL
Database	None	None	Accounts, characters, positions — never money
Default chain	In-process mock	In-process mock	The public testnet
Lines of Kei in the client	src/economy.ts, ~200	lib/market.ts	src/client/Controllers/Wallet.ts
Play it	/examples/button	/examples/carpet-markets	mmo.keicoin.org
Source	keicoin-org/button	keicoin-org/carpet-markets	keicoin-org/world-of-wonder

Which primitives each one exercises

A blank cell is not a gap in the SDK. It is a primitive that example had no honest reason to use.

Primitive	Button	Carpet Markets	World of Wonder
Kei.start() — player wallet	✅	✅	✅
Kei.server() — issuer	✅	✅ (one account per coin)	✅
token.issue	✅	✅	✅
mint / burn	✅	✅	✅
transfer	✅		✅
pay / onPayment	✅ (exchange desk)	✅ (launch fee)	✅ (exchange desk)
items.create / items.mint	✅		✅
commit / claims.add	✅
market.sell / accept / cancel		✅	✅ (market.offer, Browse / Sell / Mine)
market.price / trades		✅
wallet.summary	✅	✅	✅
faucet	✅	✅	✅

Start from one instead of cloning it

Each example is a template the scaffolder writes for you, renamed and with your own currency already in it:

npm create kei-game my-game                                    # star-clicker, the default
npm create kei-game my-mmo -- --template world-of-wonder
npm create kei-game my-launchpad -- --template carpet-markets

Cloning the repository directly gets you the same files under the original name.

The three templates are published

create-kei-game@0.2.0 scaffolds Button, Carpet Markets, or World of Wonder. Cloning a repository directly remains useful when you want the complete worked application rather than a starting template.

What all three have in common

Three properties are deliberate in every one of them, and they are the properties worth copying:

• No balances table. Not one of these games stores a balance, an inventory row, or a holdings record. balanceOf and ownedBy are the only source of truth, and every one of these servers can be stopped and restarted without a player losing anything.
• The server never signs for a player. A purchase is two signed transactions — the player signs the payment, the issuer signs the delivery — because a game cannot sign for a player's wallet and there is no API pretending otherwise. See the security rules.
• What the server does own is design, not custody. What a press is worth, what a sword costs, which coins exist. Those are opinions a chain has no business holding.

What none of them are

Nothing here holds value

That is a design constraint rather than a disclaimer. There is no mainnet, and the hosted copies run against mock chains that reset when the process or the Durable Object holding them goes away. They are demos, not services.

• Button counts its own presses, because in single-player nothing else can see them. That is a real trust hole with a ceiling on it, written down in the source rather than hidden.
• Carpet Markets has one open quote per address, because a Kei transfer carries no memo and an arriving payment says only who sent it and how much. Two browser tabs racing is a thing you can do to yourself.
• Carpet Markets is a satire of a real pattern that has taken real money from real people. It is worth playing precisely because the coins are worthless; it is not worth copying anywhere they are not.
• World of Wonder's hosted copy runs a process-local mock chain, so nothing on it survives a restart. The repository settles on the public testnet by default.

What is not finished in each

Named here as well as on each page, because a reader choosing one of these to fork deserves to find the gap before they are inside it.

	Done	Not done
Button	The balance on the pole is the chain's, with unbanked earnings shown separately beside it. Spending is graded against confirmed, available funds.	Presses are still counted by the client. It is single-player; nothing else can see them.
Carpet Markets	The client is a Next.js static export, and a card leads with the transfer policy and the creator's remaining share rather than a market cap.	The book is only as complete as the registry's account list, and the replies are the one piece of state here that is not a block.
World of Wonder	The auction house's screen and mechanism: Browse, Sell and Mine over player-signed offers, with both legs settling in one block and an end-to-end test that says so.	Equipping, loot and quest rewards still run on upstream's inventory tables, and the trainer still spends player_data.gold. The hall's in-memory roster is bounded and incomplete by design.

Continue

• Button — a 3D clicker with a real economy.
• Carpet Markets — a launchpad with a real peer-to-peer order book.
• World of Wonder — a multiplayer RPG whose gold is not in its database.
• Integration model — the two halves every one of these is built from.
• Project status — what works today, and what is scheduled rather than shipped.