Akari

Nikoli introduced Akari, also called Light Up, in Puzzle Communication issue 56 in 2001. The puzzle asks you to place bulbs on a grid so every open square receives light while numbered walls see exactly the required number of bulbs. Each bulb shines horizontally and vertically until a wall blocks the beam, and no two bulbs can see each other. Solving Akari trains spatial reasoning and constraint satisfaction. Place your first bulb and light up the grid.

1. Open the Akari grid and scan every numbered wall. Each number tells you how many bulbs sit in the four cells directly adjacent to that wall.
2. Click an open cell to place a bulb. The bulb illuminates its row and column in both directions until a wall blocks the light.
3. Check that no two bulbs see each other along an unobstructed row or column. If they do, remove one.
4. Verify that every numbered wall has exactly its required count of adjacent bulbs. A 0 wall means no bulbs touch it at all.
5. Confirm that every open cell on the grid is lit by at least one bulb. The puzzle is solved when all cells glow and all wall numbers are satisfied.

• A bulb shines horizontally and vertically until a wall blocks it.
• Two bulbs cannot see each other along an open row or column.
• A numbered wall has exactly that many side-adjacent bulbs.
• Every open cell must be lit.
• Diagonal bulb contact is allowed.

• Use a 0 clue to mark all four adjacent cells as safe. No bulb can sit next to a 0 wall, which narrows the search immediately.
• If the number of open neighbors equals a clue's missing bulb count, place bulbs in all of them. The clue forces the placement.
• After placing a bulb, rule out every cell in its unobstructed beam. Those cells are lit and cannot hold another bulb.
• Corner clues have fewer neighbors and often force the opening. Solve them first to build momentum.
• Separate illumination checking from clue counting. A cell can be lit by one bulb and still need another bulb adjacent to a wall for a different reason.

• Nonogram: Nonogram uses row and column number clues to reveal a hidden picture, offering a different style of grid deduction.
• Minesweeper: Minesweeper uses numbered cells to locate hidden mines, sharing the constraint-satisfaction approach with Akari.

• Every placement lights up visible sections of the grid, giving instant feedback.
• Numbered walls create concrete deduction entry points.
• The illumination rule is easy to grasp but produces deep logical chains.
• Solving a grid feels like wiring a miniature circuit.
• Puzzles range from quick warm-ups to extended challenges.

Play Akari online for free on Clasica Games. Click open cells to place bulbs, watch the grid light up in real time, and remove bulbs with a second click if you make a mistake. No download or account needed. Start a puzzle and light your first row.

Akari turns a grid into a lighting puzzle. Read the wall numbers, place bulbs that illuminate without conflict, and watch the board glow cell by cell. Start a free puzzle and light up your first grid.

• Nikoli Akari rules
• Light Up overview