Chess engine / playable demo
Rolf
Rolf is created by Chess Sandbox and is an experimental chess AI in active development. It offers an accessible opponent for casual play, though it can make frequent mistakes, including significant blunders. Further training and improvements are planned to strengthen its play over time.
Getting started
Try Rolf
Click Try Rolf to open the playable board below. You start as White. The opponent is already set to Rolf and evaluation to Stockfish.
Drag or click
Drag a piece to a legal square, or click a piece and its destination. Rolf replies automatically. If a pawn promotes, choose its new piece.
Read the evaluation
The bar updates using Stockfish after Rolf’s reply. Positive scores favor White; negative scores favor Black. For example, +1.00 is about a one-pawn advantage—not a guaranteed win.
Choose Black under “Your pieces” to let Rolf move first. Use New game to restart, Undo to take back a turn, Flip board to rotate the view, and Save PGN to download your game. Increase Think time to give the engines longer to calculate.
Play against Rolf
Try a game below. Rolf needs an internet connection; Stockfish evaluates the position locally. Wait for calculation to finish before making your next move.
Start a game against Rolf. You play White by default.
Troubleshooting
Am I actually playing Rolf?
Yes. Rolf plays the opponent moves, while Stockfish only evaluates the board.
What does “M3” mean?
The evaluating engine reports a forced mate score. A positive mate score favors White and a negative one favors Black. An em dash means no evaluation is currently available.
Rolf can’t connect. What should I check?
Check your internet connection and the displayed error. If the service is temporarily unavailable, try again later.