Light Up

Each bulb lights its own cell and shines along its row and column until it hits a black wall. Place bulbs so that every white cell is lit, no two bulbs shine on each other, and every numbered wall has exactly that many bulbs directly next to it (above, below, left or right). Unnumbered walls can have any number of bulbs around them.

Puzzles are generated and checked for a unique solution; harder levels show fewer numbers.

1. Tap a white cell to place a bulb, tap again to mark it with a dot (no bulb), and again to clear.
2. Lit cells turn yellow. Light every white cell.
3. Two bulbs in the same row or column with no wall between them is not allowed.
4. Numbered walls need exactly that many neighbouring bulbs.

• 4s and 0s are free information: a 4 has bulbs on all four sides; a 0 has none.
• A 3 in a corner or on an edge forces its bulbs.
• Look for cells that only one place can light — that place must hold a bulb.