Light Up
light every square · bulbs never see each other

Play Light Up — Bulbs and Walls Logic Puzzle

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Tap cycles 💡 → · → emptyDrag marks bulb-freeB bulb · X no bulb

How to play Light Up

Place light bulbs in the white squares. Each bulb lights up its whole row and column in every direction, until the light hits a black wall.

Every white square must end up lit, but no bulb may be lit by another bulb. A number on a wall tells you exactly how many bulbs sit right next to it (above, below, left or right).

Start with the 0s and the 4s, then look for dark squares that can only be lit one way.

How to play Light Up

Place bulbs so every white square is lit, bulbs never shine on each other, and every number counts the bulbs beside its wall.

The rules

  1. A bulb lights its own square and every square in its row and column until a black wall blocks the light.
  2. Every white square must be lit.
  3. No bulb may be lit by another bulb.
  4. A number on a black wall is how many bulbs sit directly next to it (across or down). Walls without numbers can have any number.

Playing here

  1. Choose classic numbering or every wall numbered (easier), a size and a difficulty, then press New Puzzle.
  2. Tap a square to place a bulb, tap again to mark it bulb-free, a third time to clear. Or pick the Bulb or No bulb tool; drag to mark many.
  3. The light spreads as you place bulbs; clashing bulbs turn red and numbers turn green when right.
  4. Hint places one bulb or mark and explains why.

Tips

The full guide, with a worked example and common mistakes: How to play Light Up.

Questions

Does a bulb light diagonally?

No — only along its row and column, until a wall.

What does ‘every wall numbered’ mean?

An easier version where every black wall shows its number, giving you more clues.

Can a bulb sit next to a 0?

No. A 0 wall has no bulbs on any of its four sides.

How do I solve a puzzle from a book?

Open the Light Up Solver, draw the walls and numbers, and press Solve.

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