Surround

Surround is Go played offchain and settled on Starknet. Moves are signed messages between the two players, not transactions. A game touches the chain only when it needs to: to settle its result, to resolve a dispute, or to force a stalled opponent to move. Cairo checks every move it is shown, a Stwo proof can stand in for replaying them, and ranked results update both players' ratings in an onchain contract.

These pages explain the parts a player or integrator needs to trust:

• Gameplay: the rules of Go as Surround plays them, how a game is scored and every way it can end.
• Settlement: how a game played offchain becomes a result on Starknet, and what happens when a player stops cooperating.
• Ranking: how a settled ranked game updates both ratings, the model behind it and the evidence for it.
• AI anchors: the five fixed-strength KataGo opponents that hold the rank scale in place.
• Fair play: how games are analyzed for AI assistance, and how accounts that show it are labeled.
• Kifu: the ERC-721 that records a settled ranked game, minted to its winner, with its record and artwork onchain.

The life of a ranked game

1. Pairing. The matchmaker pairs two players on the same board and clock and signs a ticket that names them, the board, komi, clock, referee and prover.
2. Agreement. Each player names a fresh session key, and both wallets sign the game's terms, which carry the ticket's digest. Nothing is sent to the chain.
3. Play. Every move is signed with the player's session key and sent through a keeper, which stamps the clock and relays the move. Both clients check every signature before applying a move.
4. Settlement. When the game ends, the first transaction that needs the chain opens the game and settles it together, by a proof or by onchain replay of the signed moves.
5. Rating. Anyone may then call rate, and SurroundRatings updates both players from the result.
6. Kifu. Anyone may mint the game's kifu, which goes to the winner.

A casual game follows the same path without a ticket or a clock: it never needs to reach the chain at all unless a player wants its result recorded.

What it builds on

The channel, dispute state machine, proof adapter and SDK protocol come from arbiter, a library for offchain turn-based games with onchain settlement. Surround supplies Go: its rules as arbiter's GameRules, a thin Dojo system, a thin proof adapter, and the Go codec for arbiter's JS SDK. Ratings are arbiter's game-agnostic ratings layer with Go's constants.