Choose the kind of break you want
Easy grids use three items per category. Hard and expert grids use four, which expands the possible arrangements from 36 to 576 before clues. Difficulty is measured by the strongest rule needed by our deduction solver: easy uses direct clues and one-to-one elimination; medium adds cross-grid reasoning; hard adds ordering, gap clues or paired subsets; expert requires a counterfactual. This is algorithmic calibration, not a human solving-time claim.
Make the challenge your own
Use a pencil and printed grid for a screen-free session, or keep notes in the interactive grid. You do not need a login. Progress stays in this browser; it does not sync between devices.