Click or touch a tile to toggle its neighbors.
Click Scramble and turn off all tiles to win.
Click Explore to find algorithms.
List of puzzles and difficulties. Click a difficulty to try it.
The difficulty of a puzzle is the modulo-2 rank of the adjacency matrix, which is the base-2 logarithm of the number of reachable states. It's only a rough, but objective, estimate of the actual difficulty.
The puzzle uses html5 canvas, which is not supported directly by IE 8 or lower. Try using the latest version of Chrome for the best experience.
Nan Ma, May 2014