Make a chess app
Play the computer at the strength you pick, play a friend from a link, or train openings with a coach that spots blunders.
Ask for a chess app the way you would describe it to a friend. For example: “Chess where I play the computer, with easy, club and strong levels.” Or: “Chess I can play with my dad, I send him a link and we each move on our own phone.”
Every chess app plays by the full rules: castling, en passant, promotion to the piece you choose, check, checkmate, stalemate and every kind of draw. The rules come from chess.js, an open-source library used across the chess web.
When you play the computer, your opponent is Stockfish, the open-source engine the strongest players train against. Pick a gentle beginner level or a level no human can beat. It thinks in the background, so the board stays smooth while it does. Stockfish also powers a coach: ask for an app that “tells me when I blunder and shows the better move”, and it checks each move you make.
The board can look however you like. Ask for an inlaid wood board, a park table, pieces you drag and drop, or a 3D board you can turn. Games save as you play, so you can pick one up on another device, and finished games can be a public scoresheet for your club.
For developers, the chess reference has the rules, the engine recipe and a worked example.