Ranked clocks
Ranked games are timed; casual games are not. Time can't come from the players, who would each claim the other was slow, and it can't come from the chain, which only sees a game when it settles. So a ranked game names a referee in its terms: the public key of the keeper that relays it. Players sign moves; the referee signs time.
Both players accept the referee by signing the terms. Each keeper has its own referee key, so keepers can run in several regions, each refereeing the games nearest it.
Time controls
Both time controls run on arbiter's standard time rules:
| Time control | Settings | SDK |
|---|---|---|
| Per-turn timer | 60 s per turn; unused time doesn't carry over | rankedClock(referee) |
| Japanese byo-yomi | main time, then a number of byo-yomi periods | byoyomiClock(referee, { main_ms, periods, period_ms }) |
Under byo-yomi a turn that ends inside a period costs nothing, each period that runs out is lost, and outlasting the last one loses the game.
For rated games, SurroundRatings' owner allowlists the presets, and the
matchmaker picks among them.
How a step is timed
- A player signs a step and hands it to the keeper.
- The keeper stamps it with the game's clock in milliseconds, and attests the transcript and clocks it reaches with its referee key.
- Both players verify the player's signature and the referee's attestation before applying the step.
A turn lasts while the same seat is due to act; in Go a turn is one move. Time since the last stamp accumulates against the seat, and a step whose seat has run out of time is refused. From then on the keeper may append a Flag step, and the seat that was due loses on time (reason 129).
Scoring is timed too
Proposals, acceptances and resumptions are steps like any other, charged to the seat due to act. After two passes the proposer has one turn to propose or resume; after a proposal the other seat has one turn to accept or resume. Since a game resumes at most once, only a seat that does nothing can lose on time during scoring.
Starting the clock
The referee's Start step starts the clock before the first move if nobody
moves within a grace period. The game's first stamp, whichever step it's on,
is when the game started. The channel records it, and a rated game is
dated by it, which matters for rating.
Settling a flagged game
A flag is a finished history like any other. The winner, or anyone, submits or proves it, and it settles after the response window, since the flagged player won't co-sign it.
Replay checks each player's final signature and the referee's last attestation. That one attestation covers every stamp in the game, because the clocks it signs depend on all of them. A timed batch costs one extra felt per step and one extra ECDSA check.
What the referee can and can't do
- It can't forge, reorder or settle moves. Players sign those.
- It can skew time or delay steps, so an honest player's worst case is losing on time.
- It never stamps two steps at the same sequence number. Two attestations of different transcripts at one sequence number are evidence of equivocation.
- A live referee keeps the clock running through disputes: it acknowledges a dispute, and resolving it returns the game to offchain play. A ranked game reaches forced play only while its referee is down, and the referee can return it from there on its own.
The referee key is kept apart from the keeper's account key.