About ChessDays

ChessDays is a free chess site made and run by Mussie Haile in Berlin. You can play bot characters with their own playing styles, play friends online without an account, and learn the rules from short illustrated lessons.

Why it exists

Many chess bots are a strong engine turned down. That feels nothing like playing a person. ChessDays gives every opponent a style instead: one loves captures, one attacks the king, one always castles. The bots also react as they play, with short written lines and cartoon babble.

How the bots choose their moves

Every bot uses Stockfish, the open-source chess engine, running in your browser. Stockfish scores the candidate moves; each character then adds its own preferences, such as attacking the king, trading pieces or castling early, and picks among the good-enough moves with a dose of randomness that fits its level. That's why Pip makes beginner mistakes while Nova is our strongest bot. The six characters are Pip (~400), Rosa the Gambiteer (~900), Professor Hoot (~1300), Blitz Betty (~1600), The Iron Rook (~2000), Nova (~2600). Ratings are our own rough estimates, not measured against rated players.

Their voices aren't recordings: each character has its own pitch and rhythm, and the site turns their lines into cartoon babble as you play. Read more on the character pages.

How the lessons are made

The lessons follow the official rules of chess (the FIDE Laws of Chess). The positions and move sequences they use are checked by automated tests with chess.js, a chess rules library, before each release. Each lesson shows when it was last updated.

How ChessDays is paid for

Playing is free with no limits, and there are no ads on the game screen. The engine runs on your own device, so a bot game costs the site almost nothing. Google ads help pay for the site. They can show only on the Learn page and the lessons under /learn/, except the six tactics lessons with a practice board (fork, pin, skewer, discovered attack, back-rank mate, and king and queen checkmate), and only if you accept them in the privacy banner. Every other page, this one included, shows no ads. The privacy policy explains what the site stores and sends.

Contact

Found a mistake in a lesson, or a bot that misbehaves? Write tocontact@mussiehaile.com. Full provider details are in theImpressum.