What is Light Up (Akari)?
Light Up is a logic puzzle where you place light bulbs on white tiles until every white tile on the grid is lit. It became known in Japanese puzzle magazines as Akari, which means light, and is sometimes called the gallery puzzle because it feels like lighting up a dark room.
Here the grid is the floor of a gallery after closing time. When you place a bulb, warm yellow light spreads in beams along its row and column, the wooden floor glows, and the beam stops at the brick pillars. Light the last dark tile and the whole room switches on while framed paintings appear on the walls and pillars.
What are the exact rules?
There are four rules. Light travels across and down until a pillar, every white tile must be lit, no two bulbs may shine on each other, and each numbered pillar needs exactly that many bulbs next to it. Every board has exactly one layout that satisfies all four.
| Rule | Meaning |
|---|---|
| Light | A bulb lights its own tile and every tile in the same row and column until a pillar or the edge. Light never goes diagonally |
| Light everything | Every white tile must receive light from at least one bulb |
| No shining on each other | Two bulbs may not share a row or column without a pillar between them. If they do, both turn red |
| Numbered pillar | The number is how many bulbs touch the pillar above, below, left and right. Too many turns the plate red |
| Plain pillar | It only blocks light and puts no limit on nearby bulbs |
Where should I start? Standard patterns
Look first at any 4, a 3 on the edge, a 2 in a corner and every 0. These numbers settle their neighbors immediately and give you your first bulbs.
| Pattern | What it tells you |
|---|---|
| A 4 | All four neighbors are bulbs |
| A 3 on the edge (three open neighbors) | All three open neighbors are bulbs |
| A 2 in a corner (two open neighbors) | Both open neighbors are bulbs |
| A 0 | None of its four neighbors is a bulb. Mark them with dots |
| A 3 with four open sides | The four diagonal tiles can never hold a bulb because each of them always sees a neighboring bulb |
| A 1 with two candidates left | The diagonal tile that sees both candidates cannot hold a bulb |
| An isolated tile boxed in by pillars | Nothing else can reach it, so it must be a bulb itself |
How do I get unstuck?
Pick one dark tile and count the places that could still light it. If only one place is left, that place is a bulb. This single question solves most boards from start to finish.
- Clear the numbers first. Handling every 4, edge 3, corner 2 and 0 often settles almost half the board.
- Use dots freely. Dot every tile that cannot hold a bulb and the remaining candidates stand out. Tap a dot once more to clear it.
- Look for lonely tiles. Tiles walled in by pillars see very few other tiles, so their candidates shrink fast.
- A full number means dots. If a 2 already has two bulbs, its other neighbors cannot hold a bulb.
- Still stuck? Check and Hint. Check shows bulbs that differ from the answer, bulbs that see each other and overfull numbers in red. Hint first removes a wrong bulb, and otherwise places one correct bulb that follows from the current board.
How do the sizes differ?
6×6 is a practice board with plenty of numbers, 8×8 is the standard board with many numbers removed, and 10×10 keeps only the numbers needed for a single answer.
| Size | Pillars | Bulbs to place | Numbers | Target time |
|---|---|---|---|---|
| Easy 6×6 | 8 to 12 | 5 to 11 | Most kept | Under 1.5 min |
| Normal 8×8 | 12 to 19 | 9 to 16 | About 70% removed | Around 4 min |
| Hard 10×10 | 18 to 29 | 14 to 23 | Only what is needed | 8 min or more |
The result screen shows your time and a title. Finish within half the target time and you are a Speed of light curator, within the target and you are a Seasoned curator. Best times are kept separately for each size.
How are the boards made?
First pillars are scattered with point symmetry around the center, then bulbs are placed one by one on dark tiles until everything is lit, which becomes the answer. Every pillar gets the count of bulbs touching it, and a solver checks that the answer is unique.
If there are two answers, a tile where they differ becomes a pillar and the check runs again. Once the answer is unique, numbers are removed one at a time as long as the answer stays unique. That is why every board has its own pillar shape and its own set of numbers, and no board ever needs a guess.
What is the daily puzzle?
The daily puzzle is an 8×8 board that changes every day and is the same for everyone on the same day. It switches at midnight Korea time and counts toward your daily streak once solved.
To race a friend on the same board, solve the daily puzzle together and share your time with Share result. The result card also notes how many hints and checks you used.
Controls
- Phone and mouse: each tap on a white tile cycles bulb → dot → empty. The right mouse button only places or clears a dot.
- Keyboard: arrows or WASD move, Space or Enter cycles bulb → dot → empty, X dot, Backspace clear, Z undo, H hint, C check.
- Buttons: Undo steps back one move at a time. The bulb counter at the top shows lit tiles out of all white tiles.
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