In Memoria, the game is all about finding two cards that match together. This is done by repeatedly turning over two cards, thus revealing their location on the playing field. The memory aspect of the game comes in from having to remember where the card that matches the one you just turned over is.
Overall, Memoria is a well done version of the matching game many of us played as kids. While lacking in some areas, it comes highly recommended for fans of the genre, in hopes that a future update will add some sound effects.