Medium Light Up
Medium Light Up puzzles are 8×8 and need placement reasoning around numbers: compare every way to put a wall's bulbs and mark the cells they all agree on.
Medium puzzles need at least one of these techniques, and may use any easier one:
- Around a number
- Every way to put this wall's bulbs agrees on the marked cells, for example by always lighting them.
How to play
Light Up is a logic puzzle on a grid of white cells and black walls. Place bulbs in white cells so that every white cell is lit. A bulb lights its whole row and column until a wall stops the light, no bulb may shine on another bulb, and a numbered wall has exactly that many bulbs directly beside it.
Easy puzzles are 7×7, Medium 8×8, and Hard and Expert 10×10. Every puzzle here has exactly one solution that logic alone reaches, and its level is set by the hardest technique it needs.
- Every white cell must be lit, by a bulb on it or by a bulb in its row or column with no wall in between.
- A bulb's light stops at the first wall.
- No bulb may stand in another bulb's light.
- A numbered wall has exactly that many bulbs directly above, below, left or right of it; a plain wall can have any number.
Playing on this site
- Tap a white cell to place a bulb, tap again for a dot that marks it as bulb-free, and once more to clear it.
- Drag across cells to paint the same mark along the way; the whole drag is one undo step.
- With a keyboard, use the arrow keys to move and Space to cycle the mark.
- Lit cells are tinted, so dark ones stand out. A number dims once its bulbs are all placed and turns red if it has too many.
- Dots are only a helper: the puzzle is solved as soon as every bulb is in place.
- Hint points out misplaced bulbs and dots first, then names the next technique and highlights where it applies.
- Your puzzle is saved in this browser, so you can come back to it later.