Puzzle Grid
Flip a grid of lights until every one is off, but each press also toggles its neighbours. Five boards from 3x3 to 6x6.
Every cell on the board is a light that is either on or off. Pressing a cell flips that light and the lights directly above, below, left and right of it. Your task is to turn the entire board dark in as few presses as you can.
Boards are created by scrambling a solved grid with a known set of presses, so every puzzle is guaranteed to be solvable. Pressing the same cell twice cancels itself out, which is why the order of presses never matters, only which cells you press an odd number of times.
There are five levels, growing from a 3x3 grid to a 6x6 grid. Each level shows a par move count, and finishing at or under par earns the full 100 points for that level.
How to play
Press any light to flip it and its direct neighbours. Work through the board until nothing is lit. If you get stuck, the Hint button highlights a cell that still belongs to the solution, and New board deals a fresh puzzle at the same size. Clearing a level unlocks the next, larger grid.