Lights Out

It's a so-called Lights Out game.

The rules are simple, just tap any square to turn off all the lights!
The top, bottom, left, and right of the square you tapped will switch between lit and unlit.
It's a simple operation, but it's surprisingly difficult, so you can expect it as a brain training for adults and the elderly.

In this app, you can enjoy 2 types of mode, one is to clear 100 stages prepared in advance, and the other is to create random questions.

In random mode, you can choose from 4x4 squares to 7x7 squares, so you can enjoy the difficulty that suits you.