It is time-tested samegame of a puzzle game.
I think that he enjoys himself to anyone simply and it gets with a simple rule.
If the same piece that has adhered vertically and horizontally is chosen and clicked, a piece will disappear.
The upper piece will fall and fill the crevice after a piece disappears.
If a lot is erased as much as possible, a score will go up.
It is game over when the piece connected two or more is lost.