What is Akari?
Akari, also called Light Up, is a Japanese logic puzzle played on a grid of white cells and black clue blocks. Your job is to place bulbs in white cells until every open cell is illuminated.
A bulb lights its own cell and shines horizontally and vertically until the light reaches a black block. Bulbs may not shine directly on one another, and numbered black cells tell you exactly how many bulbs must sit beside that block. This free Akari online game includes several grid sizes and difficulties, with every base puzzle checked for a unique solution.
- Place bulbs only in white cells.
- Light travels in straight lines until it hits a black cell.
- Every white cell must be lit by at least one bulb.
- No two bulbs may see each other in the same uninterrupted row or column.
- A numbered black cell must touch exactly that many bulbs orthogonally.
How to play Akari online
Click or tap a white cell to place a bulb. Tap it again to add a small marker, and tap once more to clear the cell. The marker is optional, but it is helpful when logic proves that a square cannot contain a bulb.
Use Check when you want feedback without revealing the whole answer. Hint adds a correct bulb or clears an incorrect mark, Solution shows the full placement, and New puzzle loads another unique Light Up puzzle for the selected size and difficulty.
- Start with black cells numbered 4, because all four neighbours must be bulbs.
- A 0 clue means none of its neighbouring white cells can contain a bulb.
- When a white cell can only be lit from one direction, that direction usually forces a bulb.
- Avoid placing two bulbs in the same open corridor.
- Use markers to protect cells that a numbered clue has ruled out.
Akari rules
The Light Up rules are compact, but they create a satisfying blend of local counting and long-range visibility. A numbered block only cares about the four cells touching its sides. A bulb, however, affects every cell it can see along a corridor.
A completed Akari puzzle has no dark white cells, no bulb conflicts, and every numbered block satisfied. Blank black cells are simply walls: they stop light, but they do not add a number constraint.
- Black cells block light.
- Blank black cells have no count requirement.
- Numbered black cells count adjacent bulbs only, not diagonal bulbs.
- A bulb can light many cells in its row or column.
- Two bulbs conflict if there is no black cell between them.
Akari strategy tips
Good Akari strategy starts around numbered blocks. A 4 fills every side, a 0 excludes every side, and a 3 beside a wall or corner often becomes almost as forceful as a 4.
After the obvious clues, switch to illumination logic. Look for dark cells that have very few possible bulb positions. If only one cell can light a square without breaking a clue or seeing another bulb, that placement is forced.
- Mark impossible bulb cells around 0 clues.
- Fill forced neighbours around 3 and 4 clues.
- Scan each corridor for bulb conflicts before committing.
- Use dark cells with one possible light source as anchors.
- Combine clue counting with corridor visibility instead of guessing.
Akari grid sizes and difficulty
Small Akari puzzles are ideal for learning how numbered blocks and light corridors interact. Larger Light Up grids create longer sight lines, more blank walls, and more places where one bulb can solve one problem while creating another.
Easy puzzles use more direct numbered clues. Medium puzzles remove more numbers and ask for corridor scanning. Hard Akari puzzles have larger grids and fewer local givens, but each base board still has one solution so the intended path is deduction, not trial and error.
- 7x7 Akari is a friendly starting grid.
- 9x9 Akari gives a balanced online puzzle challenge.
- 11x11 Akari adds longer visibility chains and deeper strategy.
- Easy, medium and hard change clue density and solving pressure.
- Board rotations and flips add variety while preserving unique solutions.