Rewarded for other moves

A move that is not Stockfish’s first choice drops its rating by 100. Deviating makes the game easier.

Your move

How it works

  • Set Stockfish’s strength with the slider.
  • Add rules to make Stockfish stronger or weaker as you play.
  • Undo takes back your move and Stockfish’s reply.
  • After the game, you can review every move.

Rewarded for other moves

A move that is not Stockfish’s first choice drops its rating by 100. Deviating makes the game easier.

Your own rules

A rule is a trigger, an effect and an amount: engine top move, any other move, capture, non-capture, a blunder (graded as the review grades it), check or promotion, set to make Stockfish stronger or weaker. Named modes live under Game modes, with the rules already on; /play is the blank customiser.

The engine follows you

Stockfish’s rating goes from 0 to 3190. In a “don’t” mode, breaking the rule makes Stockfish stronger. In a “reward” mode, doing the thing makes it weaker. With no rules, it’s a normal game.

Summary, link and review

When a game ends you see how you did — blunders, mistakes and the costliest move — and you can open it as a full game review. Every finished game gets its own link. To start from a position instead, use the sandbox board.