Credits
This site stands on excellent open work. Thank you to the people behind it.
Chess pieces
Piece artwork by Colin M. L. Burnett (“Cburnett”), used under the author’s multi-licence terms; we use it under the 3-Clause BSD licence. See PIECES-LICENSE.txt.
Chess rules
Move generation and PGN/FEN handling in the browser use chess.js 1.4.0 by Jeff Hlywa, under the 2-Clause BSD licence. See CHESS-LICENSE.txt.
Typography
Headings are set in Newsreader (Production Type) and body text in DM Sans (Colophon Foundry), both self-hosted under the SIL Open Font License 1.1. See FONT-SERIF-LICENSE.txt and FONT-SANS-LICENSE.txt.
Demo puzzles
The 300 exercises include eleven introductory examples and a selected, authorized public sample from Plyvero’s practice collection. Positions and recorded solution lines were checked for legality. The difficulty labels are approximate, and the recorded lines are not a claim to list every possible alternative.
Historical games
Six selected historical game scores are presented as factual move records from the PGN Mentor event archives, without source annotations. Study prompts were written for this site. This selection does not imply rights to redistribute those archives as a whole.
Icons
Interface icons were drawn for this site.