The full logical solve of the hard Light Up for September 15 to September 21, 2026, 14 × 14. 43 steps, 5 techniques, no guessing. Step through it, or jump to any step below.
The 0 at row 1, column 4 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 1, column 8 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 2, column 11 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 3, column 14 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 6, column 5 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 10, column 7 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 10, column 11 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 12, column 11 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 12, column 12 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 13, column 9 has no bulbs beside it, so none of its open sides can take one.
The 0 at row 14, column 11 has no bulbs beside it, so none of its open sides can take one.
The 2 at row 2, column 8 still needs two bulbs and has exactly two open sides. Every one takes a bulb.
The 2 at row 3, column 9 already has two bulbs beside it. Its other open sides get no bulb.
The 2 at row 5, column 4 still needs two bulbs and has exactly two open sides. Every one takes a bulb.
The 2 at row 5, column 14 still needs two bulbs and has exactly two open sides. Every one takes a bulb.
The 2 at row 5, column 8 still needs two bulbs and has exactly two open sides. Every one takes a bulb.
Nothing else can light the cell at row 1, column 6: every cell that sees it is lit, dotted or behind a black cell. It needs its own bulb.
Nothing else can light the cell at row 2, column 5: every cell that sees it is lit, dotted or behind a black cell. It needs its own bulb.
Only one cell can still light the cell at row 2, column 14: the one at row 1, column 14. The bulb goes there.
Only one cell can still light the cell at row 3, column 10: the one at row 3, column 12. The bulb goes there.
Only one cell can still light the cell at row 6, column 4: the one at row 7, column 4. The bulb goes there.
Only one cell can still light the cell at row 9, column 11: the one at row 8, column 11. The bulb goes there.
Nothing else can light the cell at row 7, column 10: every cell that sees it is lit, dotted or behind a black cell. It needs its own bulb.
Only one cell can still light the cell at row 10, column 10: the one at row 11, column 10. The bulb goes there.
Only one cell can still light the cell at row 10, column 12: the one at row 10, column 14. The bulb goes there.
Only one cell can still light the cell at row 13, column 12: the one at row 13, column 14. The bulb goes there.
Nothing else can light the cell at row 14, column 8: every cell that sees it is lit, dotted or behind a black cell. It needs its own bulb.
The 1 at row 13, column 8 already has one bulb beside it. Its other open side gets no bulb.
Only one cell can still light the cell at row 10, column 8: the one at row 9, column 8. The bulb goes there.
The 1 at row 10, column 1 still needs one bulb and has exactly one open side. It takes the bulb.
The 1 at row 1, column 2 still needs one bulb and has exactly one open side. It takes the bulb.
The 1 at row 12, column 1 still needs one bulb and has exactly one open side. It takes the bulb.
Nothing else can light the cell at row 2, column 3: every cell that sees it is lit, dotted or behind a black cell. It needs its own bulb.
Nothing else can light the cell at row 6, column 1: every cell that sees it is lit, dotted or behind a black cell. It needs its own bulb.
The 1 at row 7, column 1 already has one bulb beside it. Its other open side gets no bulb.
Only one cell can still light the cell at row 8, column 1: the one at row 8, column 3. The bulb goes there.
Only one cell can still light the cell at row 10, column 6: the one at row 8, column 6. The bulb goes there.
Nothing else can light the cell at row 12, column 7: every cell that sees it is lit, dotted or behind a black cell. It needs its own bulb.
Suppose a bulb sat at row 13, column 5. Its light closes the cells it reaches, and the 2 at row 12, column 6 would be left without room for its bulbs. So that cell has no bulb.
Suppose the cell at row 12, column 4 had no bulb. That forces bulbs at row 14, column 4 and row 12, column 5, and then the cell at row 13, column 6 would have nothing left to light it. So it takes a bulb.
The 1 at row 13, column 4 already has one bulb beside it. Its other open side gets no bulb.
The 2 at row 12, column 6 still needs one bulb and has exactly one open side. It takes the bulb.
Only one cell can still light the cell at row 14, column 4: the one at row 14, column 5. The bulb goes there.