How to play
Lantern Logic is a Queens-style logic puzzle. The board is a square grid of N×N cells split into N coloured regions. Your job is to light N lanterns.
The rules
One per row, column and colourEvery row, every column and every coloured region holds exactly one lantern.
Lanterns never touchNo two lanterns may be neighbours, and that includes the four diagonal neighbours. Lanterns that break a rule glow red.
Every lantern rules cells outA lantern clears the rest of its row and column, every cell around it, and the rest of its colour. With auto-cross on, these crosses appear for you.
Each puzzle has exactly one solution and can be solved by logic alone, without guessing.
Controls
Tap to cycleTap a cell once for a cross (a note that no lantern goes there), twice for a lantern, and a third time to clear it.
- Drag across empty cells to cross them all out in one go.
- Undo steps back one move (Ctrl+Z or ⌘Z on a keyboard). Restart clears the board, and can be undone too.
- Hint makes the next logically forced move and tells you why. You get three free hints a day.
- Keyboard: move between cells with the arrow keys and press Space or Enter to cycle a cell.
- Colour patterns add a small shape to each region, so the board never relies on colour alone.
Scoring
Three stars for a solve with no hints and no mistakes (a mistake is placing a lantern that breaks a rule). Two stars for at most one hint and three mistakes. One star for any solve. Your time and stars make the share text, for example “Lantern Logic Daily #12 — 7×7 in 2:41 ✨✨✨”.
Solving tips
Small regions firstA region with only a few free cells is the best place to start. When one cell of a row, column or colour is left, the lantern must go there.
Regions trapped in one lineIf every free cell of a colour lies in one row, that colour's lantern will use that row, so every other cell of the row can be crossed out. The same works for columns.
Count lines. If two colours fit only inside the same two rows, those two rows belong to them, and every other colour can be crossed out of those rows.
Try a lantern in your head. If a lantern on a cell would leave some row, column or colour with no space at all, that cell must be a cross.
Where does the puzzle come from?
The same family of puzzles is known as Queens puzzles and as one-star Star Battle. Lantern Logic has its own boards: every one is checked by a solver for a single solution and by a logic rater to make sure no guessing is needed.