Pack 12 Chess notation

Chess notation turns algebraic chess notation into regex practice. Squares, moves, captures, castling and promotions all follow a strict grammar, which makes them good material for ranges, optional parts and alternation.

You start with a single square: e4 and h8 are caught, while i4 and e9 are off the board and spared. Then come piece moves like Nf3, castling written O-O or 0-0, captures like Bxf7 and promotions like e8=Q. Knowing chess helps, but every board explains its rule, and the traps are moves no game could produce.

Every level also has hidden checks: words you don’t see. Passing the words on screen solves a level; passing the hidden checks too ranks it.

The Character classes track covers the ranges used here. For more notations, Music & rhythm and Chemistry work the same way.