Playfield Arcade

PRACTICE COLLECTION

Test a complete row-chasing plan

Make a first-row choice, chase each resulting row and inspect the final row. Distinguish a valid full solution from a failed starting choice and from an unproved claim of minimum moves.

Print these three studies with answers

Start with a decision

TRY IT 1 · lights-toggle-2

Cross presses toggle side neighbours; ● on, ○ off
C1C2C3C4C5
R1
R2
R3
R4
R5

What can you justify?

In the toggle sandbox, apply R3C3. Will R2C3 be on or off afterwards?

Written explanation

R2C3 starts off and is toggled 1 time. An odd number reverses it, so it finishes on. Diagonals do not belong to a press’s cross.

Play the complete starting board →

This question begins at the displayed checkpoint. The full practice link starts at the board’s opening position.

TRY IT 2 · lights-cancellation-2

Cross presses toggle side neighbours; ● on, ○ off
C1C2C3C4C5
R1
R2
R3
R4
R5

What can you justify?

In the toggle sandbox, apply R3C3 then R3C3. Will R2C3 be on or off afterwards?

Written explanation

R2C3 starts off and is toggled 2 times. An even number leaves it as it began, so it finishes off. The two identical presses cancel as light operations, even if an intermediate sandbox board is dark.

Play the complete starting board →

This question begins at the displayed checkpoint. The full practice link starts at the board’s opening position.

TRY IT 3 · lights-order-2

Cross presses toggle side neighbours; ● on, ○ off
C1C2C3C4C5
R1
R2
R3
R4
R5

What can you justify?

In the toggle sandbox, apply R2C2 then R2C3. Will R2C4 be on or off afterwards? Reversing the order must give the same final pattern.

Written explanation

R2C4 starts off and is toggled 1 time. An odd number reverses it, so it finishes on. Each cell has the same odd/even toggle count in either order. This compares final patterns, not intermediate boards.

Play the complete starting board →

This question begins at the displayed checkpoint. The full practice link starts at the board’s opening position.

TRY IT 4 · lights-chasing-2

Cross presses toggle side neighbours; ● on, ○ off
C1C2C3C4C5
R1
R2
R3
R4
R5

What can you justify?

Choose no first-row presses. The first lit square in row 1 is R1C1. Which row-2 button clears it as the next row-chasing step?

Written explanation

Press R2C1, directly below R1C1. This is a row-chasing step for the zero first-row choice, not a promise that the final row will be dark. Reset and test another first-row pattern if the full chase leaves lights on.

Play the complete starting board →

This question begins at the displayed checkpoint. The full practice link starts at the board’s opening position.

Apply the ideas to a complete board

These are fixed original studies, not new daily puzzles. The three study links below and this collection’s printable pack use identical starting positions. Their checked solution routes are included on each practice page. A collection’s technique drills may also appear in its lessons.

The order uses a repeatable rule trace, not a human difficulty score. A shorter trace is not guaranteed to feel easier. Lights studies are ordered by their construction plans.

Playfield Arcade · Updated 3 October 2026 · AI-assisted writing and code; examples checked against explicit constraints. Our method · Report a correction