A.C.A.S Frequently Asked Questions

While we support the most popular chess websites like Chess.com and Lichess.org, A.C.A.S is not intended to be used against other players without their consent. It is not ethical to use it to cheat, and you risk getting banned. The intended use is for self-improvement, analysis, or playing by yourself. Do not just follow the moves A.C.A.S gives during online matches against real opponents.

To play legitimately, vary your move times, avoid perfect accuracy, allow position swings, be mindful of "blurs" (switching browser tabs), balance speed and accuracy, limit fast moves in long games, match your rating, and avoid showing extreme consistency. AI detection systems track these types of behavioral patterns to spot unfair play, so it's best to play honestly. For learning purposes, you can disable the Moves On External Site setting to only see advice when you choose, allowing you to improve your skills naturally.

If A.C.A.S is not working, the supported site may have changed or become unsupported. Please report issues so we can make updates. It's also possible that edge cases—such as unusual devices or rare Linux distributions—may cause problems. Our goal is for A.C.A.S to work on most devices, so inform us if you encounter persistent issues. Before reporting or giving negative reviews, please read the troubleshoot page.

Yes, A.C.A.S offers an automove setting (a bot that can play for you) which is currently only supported on Chess.com. This setting is hidden by default to prevent misuse, as most people would use automove in online matches, which is against Terms of Service. Automove exists mainly for debugging and quality control. For developer instructions, see the development page.

Chess engines play differently than humans, making it easy for detection systems to catch statistical anomalies. For example, chess.com bans around 16,000 players for fair play abuse each month. Most bans occur not because A.C.A.S is directly detected, but because of suspicious behavioral patterns like move times or high accuracy. A.C.A.S cannot make you play like a human—you are responsible for fair play. To avoid bans, do not use A.C.A.S against other humans.

Move

A "move" in a chess engine refers to each time a piece is moved from one square to another.

Half-Move (Ply)

A single action by one player. A complete turn has two plies: one for White and one for Black.

Depth

The number of plies (half-moves) the engine analyzes ahead. A higher depth leads to stronger moves but takes more time.

Evaluation (Eval)

A numerical value indicating who is ahead in a position. Positive means White is better; negative means Black is better. A.C.A.S shows this visually with a bar next to the board.

Nodes

The number of positions the engine has checked. More nodes means deeper and more accurate calculations.

NNUE (Neural Network)

A neural network-based evaluation, letting engines make more human-like and accurate assessments of a position.

Movetime

The time given for the engine to think before making a move. More time generally gives stronger moves.

Chess Elo (Rating)

A numerical measurement of a player’s or engine’s playing strength. Beginners: under 1000; club players: 1600–2200; grandmasters: above 2500; top engines: above 3500.

FEN

Forsyth–Edwards Notation: describes the exact position of all pieces on the chess board using a standard string. Example starting position: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR