💡 Light Up Puzzle: Place Cats, Illuminate the Grid

What Is a Light Up Puzzle?

A Light Up puzzle (also known as Akari) is a logic puzzle where you place light bulbs on a grid to illuminate every white cell. Each bulb sends light in four directions — up, down, left, and right — until it hits a black wall. Numbered black cells tell you exactly how many bulbs must be placed in their four adjacent cells. No two bulbs can see each other in the same row or column.

Light Up puzzles were created by Nikoli, the Japanese puzzle publisher behind Sudoku. They're a pure spatial reasoning puzzle — no math required, just logical deduction about lines of sight and adjacency.

How to Play Light Up Puzzles Online

1. Click a white cell to place a glowing cat (your light source). Click again to remove it.
2. Each cat illuminates its entire row and column until blocked by a black wall.
3. Numbered black cells are your clues. A "2" means exactly 2 of its 4 adjacent cells must contain cats.
4. No two cats can see each other — if two cats share a row or column with no wall between them, that's illegal.
5. Light up every white cell to win.

On mobile, long-press a cell to mark it with a paw print — useful for noting cells you know can't have cats.

Light Up Puzzle Strategy

Start with Extremes

• "4" cells — all four neighbors must be cats. Place them immediately.
• "0" cells — none of its neighbors can have cats. Mark all four neighbors right away.
• Corners and edges — corner cells can only be lit from two directions, making them easier to solve.

Use Line-of-Sight

• Once you place a cat, every cell in its row and column (until a wall) is automatically lit and cannot hold another cat.
• Look for cells that can only be lit from one remaining direction — those are forced placements.

Never Guess

If you're stuck, you've missed a deduction. Go back and check every numbered cell — there's always a logical next step. Use the Hint button if you need a nudge.

Light Up vs Sudoku

FAQ

More from MeowTrail

• Play MeowTrail — the main game with all difficulty levels
• Logic Puzzle Guide — what are logic puzzles
• Akari Puzzle Guide — history and advanced techniques
• Games Like Sudoku — 10 alternatives to try