Chessku

Chessku is a daily deduction puzzle that crosses chess with Wordle. Every square on the grid shows one number — the mobility of the piece hiding there, meaning how many legal moves it has, blocked by its neighbours and bounded by the board edge. You drag pieces from a palette onto the squares trying to reproduce those numbers, and each guess comes back with Wordle-style colours: green for the right piece on the right square, orange for the right piece in the wrong place, red for a piece that isn't in the solution at all. Five sizes run from a 3×3 board up to an 8×8 with sixty pieces on it, and everyone gets the same board each day.

The idea just turned up one morning, with no better justification than wanting to know whether the mechanic worked. I wrote it as a single HTML file to find out. It did, so the rest was making it presentable.

The wrinkle is that the numbers alone don't pin down an answer — several arrangements produce the same mobility pattern, so you can't solve it on paper. You have to probe, which makes it closer to Mastermind than Sudoku. Porting it to Next.js, I kept the game running as imperative DOM code inside one effect rather than rewriting it in idiomatic React, so the diff against the original file stayed readable.