Toggle Grid

Toggle Grid is our version of the familiar Lights Out puzzle. A board begins with some tiles illuminated. Pressing a tile changes five possible positions: itself and the neighbours immediately above, below, left and right. The aim is to extinguish the complete board.

How Toggle Grid works

Choose a lit or unlit tile to press. The centre tile always changes state, while neighbouring tiles change only when they exist; a corner therefore affects three positions and an edge press affects four. Pressing the same tile twice cancels both changes and returns every affected light to its earlier state.

Standard difficulty contains two independently generated 4 × 4 boards. The game shows a verified par for each board: the smallest number of tile presses in any valid solution. You do not have to reproduce the solver’s particular route. Any sequence that clears the board is accepted.

Why this is a planning puzzle

Planning begins when the value of a move depends on what it makes possible next. There is no permanently correct action attached to a single lit tile. The same press can be useful near the start of one route, wasteful in another, or necessary only after a neighbouring row has been settled.

The board also has reversible actions. Because every press is its own inverse, an experiment can be undone, but the extra presses reduce move efficiency. This makes the history of the route matter: reaching the correct final state is the main goal, while reaching it economically distinguishes a deliberate solution from repeated trial and error.

A dependable row-by-row strategy

1. Look at the top row first. Decide which first-row presses you want to test. Once that row is left behind, the row below controls whether its lights remain on.
2. Chase each lit tile downwards. If a light remains on in one row, press the tile directly below it. That is the only later press capable of changing the light above.
3. Do not repair a finished row from the side. A press in an earlier row disturbs work you already settled. Continue down the board and inspect the final row instead.
4. Use the last row as the verdict. If the bottom does not clear, undo or reset and change the first-row pattern. The rows between are then determined by the chase.

This method does not remove all thought. It turns an unfocused search across every tile into a small first-row decision followed by a sequence of consequences. On the 5 × 5 board, there are only 32 possible first-row patterns to consider—exactly the same bounded search used by the validator.

What changes between difficulty levels?

Difficulty is controlled by both board width and the exact optimal distance from the solved state. The generator does not call a board Hard merely because it looks busy; a solver must confirm that its shortest route falls inside the stated range. Results remain separate by difficulty.

How the Toggle Grid score is calculated

Clearing boards contributes 72% of the score. Move efficiency contributes 23%, comparing the number of presses used with the verified minimum. Pace contributes the remaining 5%, so thoughtful play matters far more than frantic tapping. An unfinished board receives no efficiency or pace credit.

Undo reverses the latest tile but counts as another press, because the board has still been changed again. Reset restores the starting position while retaining the presses already used in that round. These controls support recovery without hiding the cost of experimentation.

The score is a recreational measure for comparing your own attempts under the same difficulty. It does not assess intelligence, executive function, neurological health or real-world planning ability.

How boards are generated and verified

A seeded generator begins from the all-off state and applies a set of legal presses to create a reachable board. It then solves the displayed state independently. Candidates are rejected if they are already clear, repeat another board in the workout or fall outside the difficulty’s optimal-move range.

The exact solver tests every possible press pattern in the first row. For each one, the rows below are forced: a lit tile can only be cleared later by pressing directly beneath it. If the final row clears, the route is valid. The solver compares every valid route and records the shortest, including cases where one board has several solutions.

Keyboard and touch controls

Every tile is a native button with a row, column and on/off state in its accessible name. Arrow keys move within the board; Enter or Space presses the focused tile. Undo, reset, pause and difficulty controls follow the normal keyboard order. On touch screens, the 5 × 5 Hard board still keeps each tile above the minimum target size at the supported mobile width.

The complete board is inherently spatial. Its programmatic labels expose the same state and coordinates, but reading a large grid serially is slower than seeing the pattern at once. The Accessibility page records that limitation rather than treating keyboard operation alone as equivalent non-visual play.

Toggle Grid questions