Lights Out is a classic electronic puzzle game originally released by Tiger Electronics in 1995. The game features a 5x5 grid of lights that can be toggled on or off. The catch? Pressing any light also toggles its orthogonal neighbors (up, down, left, right). Your goal is simple but challenging: turn every single light off.
This free online version features 20 hand-crafted levels that progress from beginner-friendly patterns to fiendishly complex configurations. Track your moves, earn star ratings for optimal play, and compete against yourself to find the most efficient solutions.
Click or tap any lit (yellow) cell on the 5x5 grid. That cell and all of its direct neighbors (up, down, left, right) will toggle their state — lit cells turn off, and dark cells turn on. Your objective is to turn all lights off using as few moves as possible. Each level has an optimal solution, and your star rating depends on how close you get to it.
The puzzles are generated by starting from a solved (all-off) state and applying a known number of random toggles. This guarantees every puzzle is solvable. Mathematically, the Lights Out puzzle can be modeled as a system of linear equations over the Galois field GF(2), where each cell represents a variable and toggling is addition modulo 2.
A common strategy is "light chasing": work row by row from the top, toggling cells in the row below to turn off lights in the current row. After reaching the bottom, certain patterns on the last row tell you which cells in the first row to toggle before repeating. This systematic approach guarantees a solution for every solvable configuration.
Not every random configuration is solvable. On a 5x5 board, exactly 1/4 of all possible light patterns can be solved. However, this game always generates solvable puzzles by starting from the solved (all off) state and applying random toggles backwards, guaranteeing every puzzle has a solution.
The minimum number of moves depends on the specific configuration. For a 5x5 board, the maximum minimum (the hardest possible puzzle) requires 15 moves. The original Lights Out puzzle was proven to have solutions using linear algebra over GF(2), where each cell is treated as a variable in a system of equations modulo 2.
If you enjoy Lights Out, try these logic puzzles: Nonogram — fill in a grid using number clues to reveal a hidden picture. Sliding Puzzle — slide tiles into order in this classic 15-puzzle. Logic Puzzles — test your deduction skills with grid-based logic challenges.
Last updated: March 2026 · whatifs.fun