Brain Game N back is a game that helps improve your memory. You are shown a stream of cards and try to indicate when the same card you see also is the same card you saw N cards ago.

The game is pretty simply you're shown a bunch of cards your job is to hit match if the card you is the same card you saw N spots ago. If the value of N is 1 that means that if I show you a card and the previous card was the same card then its considered a match. If N is 2 then if I show you a card and the card that came two spots before the current one is the same then its considered a match.