Akari Puzzle Glossary — All Terms
X Mark — An X mark is a player-placed annotation on a white cell to indicate that no bulb should go there. X marks are not part of the official Akari rules — they are a solving aid.
Most online Akari implementations, including GridPaw, let you place X marks by right-clicking or long-pressing a cell. X marks help you track elimination logic and avoid accidentally placing bulbs in impossible positions.
Recommended for all players, especially on Medium and Hard puzzles. X marks reduce cognitive load by externalizing your elimination reasoning.
Right-click (or long-press on mobile) any white cell to place an X mark. Click again to remove it.
When a "0" cell rules out its neighbors, mark them with X. When a bulb's light makes another position impossible, mark it too.
When all but one cell in a number's neighborhood are marked X, the remaining cell must hold a bulb.
No. X marks are a convenience tool, not a rule. Experienced solvers often skip them on easy puzzles. But on hard puzzles, they are invaluable for tracking complex deductions.
Right-click on desktop or long-press on mobile to toggle X marks on any white cell. Click again to remove the mark.
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