How to play
- Put bulbs in white cells so every white cell is lit.
- A bulb lights its row and column until a black cell stops the light.
- No bulb may shine on another bulb.
- A number counts the bulbs on the four sides of its black cell.
- Tap a cell once for a bulb, twice for a dot that means “no bulb here”. Drag to place dots.
Keyboard: arrows to move, space to cycle, b bulb, x dot, delete to clear a cell, h hint, Ctrl Z undo, Ctrl Shift Z redo. On a Mac use ⌘.
Learn the logic behind itAbout unlimited Light Up
Easy grids fall to the number rules alone. Medium asks you to look one bulb ahead, and Hard needs short chains of “if a bulb went here”. Each week there is also one big, hard grid: Light Up of the week. Your progress on the current puzzle is saved on this device.