Credits & sources

Prologue Chess relies on verified chess sources. No opening line is made up: every variation comes from public references and is checked by a chess engine.

Opening theory

Names, variations and main lines draw on the standard chess literature and public opening encyclopedias (including Wikipedia and the Encyclopaedia of Chess Openings / ECO).

Opening popularity

Each opening's popularity tag is computed from the public games database of Lichess (more than 8 million games analyzed), under an open license.

Validation

Every line is run through a chess engine to rule out any dubious variation. The goal: that you learn real theory, not an approximation.

Chess pieces

The piece set shown in the app and on this site was created by RhosGFX, released under the CC0 license (public domain). Thanks to its author.

Publisher

Prologue Chess is published by AGENCE DEBORD EURL. Contact: adebord@agencedebord.com.