Light Switch

Turn off every light. Sixty levels, each one proven solvable, down to the last press.

• Puzzle Games
• Ages 6-9
• Ages 9-12
• Ages 12+
• Games for Girls
• Games for Boys

Light Switch is a lights-out style logic puzzle that runs right here in the browser. Tap a tile and it switches, along with the tiles directly above, below, left and right of it; the goal is to turn every light off. The first levels are a 3x3 grid solvable in a press or two. The last ones are 6x6 grids that can take real thought. What makes it fair is that every level's par - the smallest possible number of presses - is not a guess. It was computed with the same linear algebra used to solve the real Lights Out puzzle, over GF(2), and checked by an independent solver before the level went in. There is unlimited undo, three hints per level, nothing to download and no ads.

How to play

1. Tap or click a lit or unlit tile. It toggles, and so do its direct up, down, left and right neighbours.
2. The goal is to turn every single light off. A move counter and the level's par are shown at the top.
3. Made a mistake? Press Z or the Undo button as many times as you like, or R to restart the level from scratch.
4. Stuck? The Hint button lights up the next tile to press. You get three hints per level, and using one caps that level at two stars.
5. Finish in the par number of presses for three stars. Stars and your best move count are saved on your device.
6. Arrow keys and Space also work, for players who prefer a keyboard.

Why it is not just clicking

Every press changes five tiles at once, so an obvious-looking press to fix one stray light usually breaks two others nearby - the puzzle is entirely about seeing a few moves ahead before committing to the first one. What keeps it honest is that par is real: the levels were generated backward from a known solution and then solved independently by a second program that explores the whole possibility space mathematically, so the number at the top of the screen is a proven fact, not an estimate. The three worlds change the grid size and the shape of the puzzles, not the rule - the same logic that clears a 3x3 room in one press eventually clears a 6x6 tower in ten or more, planned out in advance.

How hard is it?

The sixty levels are sorted by measured difficulty into three worlds that grow in grid size. Small Room (levels 1-20) is a 3x3 grid with a par of one to three presses - genuinely approachable for a young child. Great Hall (21-40) mixes 4x4 and 5x5 grids with a par of three to six. Grand Tower (41-60) is 5x5 and 6x6 with a par that climbs past ten in the hardest levels - real puzzles for an adult. Each world's first level is always open, so you can jump ahead, and undo is unlimited everywhere, so there is never a reason to be stuck for good.

Is it right for younger players?

From about six for Small Room, where the grid is tiny and a mistake costs one keypress to undo. Seven- to nine-year-olds usually work through Great Hall on their own. Grand Tower is a genuine adult puzzle - several of the hardest levels are worth bringing to the dinner table. There is no timer anywhere, so nobody is rushed into a wrong move.

For parents

There are no ads, no pop-ups, no sign-up and nothing to buy. The game runs entirely in your browser and collects nothing; stars and best scores are saved on your own device and go nowhere else. We built it ourselves rather than licensing it. A level takes anywhere from five seconds to fifteen minutes, there is no clock and no penalty for undoing, so it suits a child who likes to think things through rather than react quickly.

In the classroom

This is linear algebra made tangible without ever naming it: toggling a tile is adding a vector over GF(2), and a level's par is the minimum-weight solution to a linear system - the same mathematics taught explicitly much later. For younger children it is simply planning and consequence: every move has a ripple effect, and the par score turns 'find a shorter way' into something concrete to aim for. Small Room levels fit a five-minute slot; the hardest Grand Tower levels are good material for a pair of older students to argue over.

Questions