Concentration is a minigame that appears in the Nintendo DS version of Mario & Sonic at the Olympic Games. Concentration is used as the minigame for the black and green doors of the Beijing 2008 section of the Gallery, and is based around finding pairs of matching cards.
In this game, the player is given a grid of face-down cards and must find all of the matching pairs of Emblems in it. The player turns over two cards, and will earn a point for a pair, but will lose a life if the cards that they turn over do not match. The player starts the game with 20 seconds on the timer and seven lives. Each pair of cards found adds one point to the player's total and five seconds to the timer. When there are only two cards remaining on the grid, these will be turned over automatically as a pair, and the player will be awarded a point for them as well. Each grid cleared adds two more lives to the life counter, and a new grid of face-down cards will appear onscreen. The minigame ends when the player runs out of lives or time.