a memory game where you need to match pairs of tiles. Playing is very simple - you turn over one tile and then try to find a matching tile. There are 32 levels, each getting progressively harder.

When you click on the first tile of a turn and you have exposed a matching tile in a previous turn, a message tells you that the pair is known. This indicates that you should then be able to make a match (if you have perfect recall). The scoring system incorporates this principle. In some levels, all the tiles are revealed initially for a few seconds. This makes it harder to score a perfect recall as it assumes you remember where each tile is.