Solving Techniques
Nonogram Revisited solves with nine human-style techniques, always trying the easiest first. Every one is a forced deduction: none of them needs a guess. Each guide has a diagram you can follow.
Level 1 · Easy
1. Full Line & Zero Line
A line with clue 0 is entirely crossed out, and a line whose clues plus mandatory gaps match its length is completely determined.
Level 1 · Easy
2. Simple Boxes (Clue Overlap)
Push each block as far one way and then the other; cells covered both times must be filled.
Level 1 · Easy
3. Simple Spaces (Block Length Limit)
Cross out cells no block can reach, or gaps too short for any block.
Level 2 · Medium
4. Forcing (Edge & Wall Extension)
A filled cell against an edge or a wall forces its block to grow away from the boundary.
Level 2 · Medium
5. Glue & Puncturing
Filled cells glue a block into place; a finished block is punctured by crosses on both sides.
Level 3 · Hard
6. Joining & Splitting Blocks
Join two filled groups that must belong to the same block, or split them when joining would make a block too long.
Level 3 · Hard
7. Mercury (Bouncing)
A block that would run into a filled cell right after it cannot start next to the wall, so it bounces away.
Level 4 · Unfair
8. Edge Logic & 2-Line Lookahead
Test a cell and follow its immediate effect on the crossing lines; if a neighboring line breaks, the cell is decided.
Level 5 · Extreme
9. Line Contradiction (Bifurcation)
Assume a cell, follow every forced consequence, and if a line has no valid arrangement the opposite must be true.