This is a solitaire game where the object is to find all pairs of matching objects. Initially the board is filled with small gray squares representing unknown objects. Click on a square to reveal its object, then click on another square to try to match it. If the objects are the same, they will remain revealed; if not they will disappear after a short delay. You win when all pairs are revealed. There is a 3d variation that is especially challenging.
Looking for the purple square...
In the 3d variation you'll need to keep track of the board orientation to remember where the objects were.