Light up
Place bulbs to light every white cell.
Example
Example
A bulb lights a row and column
Light travels horizontally and vertically until it meets a wall or the edge.
Step 1 of 3
4 × 4. Learn wall clues and single light sources.
4 × 4. Start with a wall that needs a bulb in every available neighboring cell.
One puzzle · Untimed · Hints available
One answer, reached by reasoning alone. No guessing.
Clear this puzzle and start it again?
Puzzle complete
On by default unless you turn it off. Saved choices are kept. Shares starts, completions, replays and error categories. For ChatGPT visits, starts and completions may include the first QuickenBrain page and country. No answers, drawings or names.
How this data is usedHelp
- Place bulbs in white cells. Light travels horizontally and vertically until a wall or the edge.
- Light every white cell. Bulbs must not shine directly on each other. Crossing light rays are allowed.
- A wall number counts bulbs directly above, below, left and right. The count must match exactly. Diagonals do not count.
- An X means no bulb here. It does not block light. Marking every unused cell is optional.
Ask which cells need light and which can still hold a bulb. An X answers only the second question.
About this practice
Place bulbs to light every white cell. Use wall numbers and light paths to decide where each bulb belongs.
Report a problem
On by default unless you turn it off. Saved choices are kept. Shares starts, completions, replays and error categories. For ChatGPT visits, starts and completions may include the first QuickenBrain page and country. No answers, drawings or names.
How this data is used