Concentration : Card Gamepedia

Nervous weakness is a winning game if you flip two cards from the face down card and get the same numbers
It is a world-famous card game that is also called "memory" or "permanism".
Collect all the cards by relying on your memory!
(Overview of Concentration)
It is a clear game if you take all the cards placed face down within the time limit.
(flow)
First, the cards are lined up face down.
The time limit countdown will start, and the game will start from here.
Turn over two cards, and when the cards with the same number are turned over, take the pair.
If you take all the cards within the time limit, the game will be cleared.
(About the stage)
This game has 20 stages in total from 1 to 20.
A new stage will be released for each clear.
The stage to be released will gradually become more difficult.
Conquer all 20 stages and become a ConcentrationMaster.