Cheating & Fair Play

The short version

Play your own moves. Don't use a chess engine, another person, or any external assistance during a rated online game. Everything else on this page is detail.

Not allowed in rated games

• Using a chess engine or any move-suggestion tool, in any form.
• Getting move help from another person.
• Playing on multiple accounts to manipulate matchmaking or ratings.
• Deliberately losing games (sandbagging) to lower your rating unfairly.
• Having someone else play on your account.

Playing against the built-in engine in Play vs Bot mode is obviously fine — it's the whole point of that mode, and those games are unrated.

How reports are handled

After every rated game, we automatically compare each player's moves against a chess engine's top choice and record how often they matched. Games with an unusually high match rate are flagged for review — you can see this on a game's replay page as an "Engine match" percentage and, if flagged, a review notice.

A flag is a signal, not a verdict: strong players naturally match an engine often, especially in the opening and in forced or simple positions. Nothing happens automatically because of a flag — a person reviews the actual game before any action is taken, the same as with a manual report.

What happens if the rules are broken

Depending on severity, we may void affected results, reset or adjust a rating, or suspend the account. Repeated or serious violations can result in a permanent ban.

Reporting a concern

See Contact Us — include the game and roughly when it happened.