Nonogram

Every cell in these puzzles can be determined through logic. No trial-and-error guessing, no 50/50 coin flips, no "pick one and see what happens." Each puzzle is generated and verified by a constraint solver that confirms deducibility before accepting it.

The grids are 15×15 with fill percentages between 40–60%. Clue lines can have up to 8 groups. You need every technique — overlap, edge logic, gap analysis, cross-referencing, and sometimes elimination chains where you assume a value and trace the consequences to find contradictions.

The difficulty here isn't that the puzzles are unsolvable — they're guaranteed solvable. The difficulty is that the logical path can be deeply buried. You might need to chain four or five deductions across rows and columns before anything visibly resolves. Patience and systematic checking are what get you through.

When you're stuck, the hint system is especially useful here. It finds one cell that's deducible right now and explains why. On Einstein puzzles, there's always a next step — the solver guarantees it. For the full solving toolkit, see the strategy guide on the Nonogram hub page.