Mahjongg Dimensions, from the puzzle studio Arkadium, takes the familiar Mahjong tile-matching game and builds it into a three-dimensional cube. Instead of a flat pile of tiles, you look at a block of tile-covered cubes that you can turn and inspect from every side. Matching is the same as in classic Mahjong solitaire, but finding the pairs now means rotating the puzzle as well as reading it.
Turn the cube to find two identical tiles that are free, then select both to remove them. A tile is free when it is not boxed in by its neighbours. In practice that means one tile in the middle of a full row cannot be picked until the tiles beside it are cleared. Remove pairs quickly to keep the cube shrinking. You are playing against the clock, and faster matches earn more points.