How to play
Tapping a lamp switches it and its direct neighbours above, below, left and right: lit lamps go dark and dark ones light up. Lamps on the edge have fewer neighbours.
Switch every lamp off to solve the board.
On each sheet exactly one set of lamps solves it, and the meter shows how many lamps are still lit. We use 6×6, 7×7 and 8×8 boards because on those sizes the solution is always unique.
Strategy and tips
- Order doesn’t matter. Pressing A and then B gives the same board as B and then A. Pressing the same lamp twice changes nothing, so a solution never needs any lamp more than once.
- Chase the lights down. Work from the top row: for every lit lamp in a row, press the lamp directly below it. When you reach the bottom, every row except the last is dark.
- Leave the edges for last when you play by eye. A corner lamp touches only two neighbours and an edge lamp three, so presses near the middle change the most at once — useful when you are looking for a lit cross to clear in one go.
- Read the bottom row. The pattern left on the last row tells you which lamps of the top row the solution presses. Press those, chase down again, and the board clears. The counting guide has the lookup tables for every board size.
- Count your presses. Each sheet tells you how many presses the solution takes; if you are far past that number, undo and look for a lamp you pressed twice.
Questions
- Why is there no 5×5 board?
- On a 5×5 board every solvable pattern has four different solutions. We only use sizes on which every board has exactly one, so a hint is never ambiguous.
- What do the levels mean?
- Easy and medium are 6×6 boards whose solutions take 4–6 and 8–12 presses. Hard is 7×7 with 14–20 presses, and expert is 8×8 with 22–30.
- Is the number of presses the minimum?
- Yes. The solution is unique and never presses a lamp twice, so it is also the shortest possible.
- Can I play with a keyboard?
- Yes. The arrow keys move the cursor, Space or Enter presses the lamp under it, H gives a hint, and Ctrl+Z and Ctrl+Y undo and redo.
- What does the hint show?
- It highlights one lamp that belongs to the solution and that you have not pressed yet. Pressing hinted lamps one by one always ends with a dark board.
- Is my progress kept?
- Yes, the board, the press counter and the timer are saved in this browser after every move, and the puzzle reopens where you left it.