Play the beloved Japanese logic puzzle Akari online — with adorable cat visuals.
Akari (あかり, meaning "light" in Japanese) is a logic puzzle created by Nikoli, the legendary Japanese puzzle publisher behind Sudoku, Kakuro, and dozens of other beloved deduction games. First published in 2001, the akari puzzle quickly became a favorite among fans of Japanese logic puzzles for its unique combination of spatial reasoning and constraint satisfaction.
In an akari puzzle, you are given a rectangular grid containing black walls and white cells. Some black cells carry numbers from 0 to 4. Your task is to place light bulbs on white cells so that every white cell is illuminated — each bulb sends light in four directions (up, down, left, right) until it hits a wall. The numbered cells tell you exactly how many bulbs sit in their four adjacent positions. And the critical constraint: no two bulbs can see each other along the same row or column without a wall between them.
Like Sudoku, Akari is a grid-based deduction puzzle with a unique solution — but instead of placing numbers, you manage lines of sight. This makes it a spatial logic puzzle rather than an arithmetic one, which is why many players find it more relaxing and intuitive than number-based puzzles. You can play akari online for free on GridPaw, where the classic puzzle is reimagined with adorable glowing cats instead of light bulbs.
Nikoli has been inventing and publishing logic puzzles since 1980. Their editorial philosophy is strict: every puzzle must have a unique solution solvable through pure logic alone. No guessing, no trivia, no luck — just deduction. This philosophy applies to all Nikoli creations, and the akari puzzle is no exception.
Akari joined Nikoli's roster of iconic puzzles alongside Sudoku (which Nikoli popularized worldwide in 2004), Kakuro (cross-sum puzzles), Slitherlink (loop-drawing), and Nonograms (pixel art by numbers). While Sudoku captured the global spotlight, Akari quietly built a devoted following among players who preferred spatial reasoning over number manipulation.
The puzzle spread internationally through Nikoli's quarterly puzzle magazine, newspaper syndication, and eventually online puzzle sites. Today, you can find akari online on dozens of websites, but the puzzle's core remains unchanged from Nikoli's original 2001 design. The name "Light Up" is the most common English localization, though purists and Japanese puzzle fans still call it by its original name: Akari.
If you are new to the akari puzzle, here are the four rules that govern every puzzle:
That is all there is to it. Four rules, infinite possibilities. The simplicity of the ruleset is what makes the akari puzzle so elegant — and so challenging on larger grids.
How does the akari puzzle stack up against other popular logic puzzles? Here is a comparison:
| Feature | Akari (Light Up) | Sudoku | Nonograms | Slitherlink |
|---|---|---|---|---|
| Core mechanic | Place bulbs, light cells | Fill numbers 1–9 | Color cells by clues | Draw a loop |
| Reasoning type | Spatial + logical | Number logic | Counting + pattern | Topology + logic |
| Math needed? | No | Basic (1–9) | Counting only | Counting only |
| Visual feedback | Real-time illumination | None until complete | Picture emerges | Loop forms |
| Origin | Nikoli, 2001 | Nikoli, 1984 | Non Ishida, 1987 | Nikoli, 1989 |
| Theme on GridPaw | 🐱 Glowing cats | Numbers | Pictures | Lines |
The akari puzzle stands out because of its real-time visual feedback. As you place bulbs, you can literally watch light spread across the grid. This makes progress feel tangible and satisfying in a way that number-placement puzzles cannot match. It is also one of the few logic puzzles where the core mechanic (illumination) is inherently visual rather than abstract.
This is the foundation of every akari puzzle solve. Start by examining numbered black cells:
After each placement, propagate the consequences: newly placed bulbs illuminate rows and columns, which may force or eliminate other placements. Repeat until no more simple deductions are available.
When you place a bulb in an akari puzzle, it illuminates its entire row and column. This means:
This "last remaining option" technique is the most common way to break through a stuck position. Scan the grid for dark cells and count how many valid positions could illuminate them.
When constraint propagation and line-of-sight elimination are not enough, use hypothetical deduction. Pick an undecided cell and mentally assume "a bulb goes here." Propagate all consequences — illumination, neighbor counts, conflict zones. If you reach a contradiction (a numbered cell gets too many bulbs, or a white cell becomes impossible to illuminate), then your assumption was wrong and that cell cannot hold a bulb.
This technique is what separates Easy akari puzzles from Hard ones. On a 12×12 grid with sparse clues, you may need to chain several hypothetical deductions before making progress. The key is to choose assumptions that affect the most cells — placing or eliminating a bulb near a cluster of numbered walls gives you the most information.
Advanced solvers mentally overlay a "shadow map" on the grid. For each undecided cell, track which directions could still illuminate it. As you place bulbs and mark impossibilities, the shadow map narrows. When a cell's shadow map shows only one viable direction, that direction is forced. This systematic approach prevents you from overlooking subtle deductions on larger grids.
GridPaw offers three difficulty tiers for the akari puzzle:
| Level | Grid | Techniques Needed | Best For |
|---|---|---|---|
| Easy | 7×7 | Constraint propagation only | Beginners, quick sessions |
| Medium | 10×10 | Propagation + 1–4 elimination steps | Intermediate solvers |
| Hard | 12×12 | Propagation + multiple elimination chains | Experienced puzzlers |
If you are new to akari online, start with Easy puzzles to build intuition. The 7×7 grid has more numbered clues relative to its size, which means more forced placements and fewer dead ends. Once you can solve Easy puzzles without hints, move to Medium. Hard puzzles are for players who have mastered all four techniques above.
The original Akari uses light bulbs — functional but visually cold. GridPaw replaces them with glowing cats: warm, round, and emotionally inviting. This is not just decoration. The cat theme serves a practical purpose: it lowers the intimidation barrier for new players. A grid full of cute cats looks like play, not homework. The warm golden illumination creates a cozy atmosphere that makes solving feel meditative rather than stressful.
The cat theme also adds a layer of emotional engagement. When you place a cat and watch its light spread across the grid, the visual feedback is more satisfying than a plain light bulb icon. This emotional connection keeps players coming back — which is why GridPaw has become a popular destination for akari online play.
Yes. "Akari" is the original Japanese name by Nikoli. "Light Up" is the English localization. Same puzzle, same rules, same logic. GridPaw uses both names.
Akari uses spatial reasoning (lines of sight, adjacency) instead of number placement. No math is needed — just careful observation and logical deduction. Both are Nikoli puzzles with unique solutions.
Yes, if it has a unique solution. All akari puzzles on GridPaw are verified to have exactly one solution reachable through pure logic. If you feel stuck, re-examine your numbered cells — there is always a deduction you missed.
Right here on GridPaw! No download, no registration, no ads. Choose from Easy (7×7), Medium (10×10), or Hard (12×12) and start solving immediately.
A "0" means none of its four adjacent cells can contain a light bulb. It immediately eliminates four positions, which often triggers a chain of further deductions.
