Light Up

Light Up (also known as Akari) is a captivating logic puzzle. Played on a rectangular grid, the game challenges you to illuminate the entire board with light bulbs—without letting any two bulbs shine directly on each other.

The grid contains black cells and white cells. Some black cells display numbers, indicating exactly how many light bulbs must be placed in the adjacent white cells (horizontally or vertically). Your task is to place light bulbs in white cells so that:

• Every white cell is lit by at least one bulb (light travels horizontally and vertically until blocked by a black cell).
• No two bulbs shine on each other (i.e., no two bulbs can be in the same row or column unless a black cell is between them).
• All numbered black cells have exactly the specified number of adjacent bulbs.

Despite its simple rules, Light Up offers deep logical deduction and satisfying “aha!” moments. Each puzzle has a unique solution that can be reached through pure reasoning—no guessing required. The game generates puzzles of varying sizes and difficulty levels, making it accessible to newcomers while still engaging seasoned solvers.

Place light bulbs in the grid to illuminate all the blank squares. Each light illuminates its own square and all squares in the same row or column, unless its path is blocked by a wall (a black square). No two lights may illuminate each other. Additionally, each numbered square must be orthogonally adjacent to exactly the number of lights indicated.

Click on a square to place or remove a light. Right-click to place a dot, marking the square as definitely not containing a light.