This might be the most challenging memory game because the images do not match exactly. A parent, teacher or another player picks 10-20 cards of matching type and places them in a grid. The player turns over two cards. If the card types are the same, the player keeps the pair. For instance, a player turns over a galaxy, then turns over another galaxy. The player would keep those cards. However, if the player turned over a galaxy, then turned over a planet, the cards would be flipped back over and game play would continue.