Dimensions swaps the flat stack for a solid block you can spin, and the first thing to understand is that spinning is not a move. Rotation is a camera. Tiles do not shift, nothing becomes available because you turned the block, and the board seen from one side is the same board seen from the other. What rotation buys is information, and on a timed block information is the scarce resource.
One board, four views
A block layout hides roughly half its tiles behind itself at any moment. A tile is available on the usual terms: nothing resting on top of it, and at least one side exposed. On a block, exposure comes from the outer surface, so the whole shell is in play and the interior is not, including the entire back face you cannot currently see. Two matching tiles on opposite faces are a perfectly legal pair, and selecting one, rotating, and selecting the other works exactly as it should.
Turn the block all the way round before the first match
This costs a few seconds and pays for the rest of the run. Make one full rotation and register what sits on each face before touching anything, because the opening minute is when the surface is most crowded and most pairs live on different faces. Players who start matching on the face they were dealt spend the whole game rediscovering the same tiles from a new angle.
After the opening survey, rotate in half turns rather than quarter turns while hunting. The face opposite the one you are on is where the unseen half of any design tends to sit.
The clock is the opponent
Dark Dimensions is built around a short timer rather than a hard puzzle, and that changes what counts as a good move. The standard mode starts at 350 seconds and the longer variant starts at 900. Matches pay time back, so a run continues for as long as you keep finding pairs faster than the clock spends itself. The consequence is that a slow correct match and a fast correct match are not worth the same thing: hesitation is a cost even when the click is right. Black and White Dimensions is one of the layouts kept on this site.
With 350 seconds the game is a sprint, and the correct policy is to take whatever you can see immediately and let the time bonuses carry you forward. With 900 the early clock is not the binding constraint, so the first minute is better spent on the awkward tiles, the ones on the edge between two faces and anything sitting under a stack three deep, while you can still afford to think.
Chains pay twice
Consecutive matches made without a long pause are rewarded in most versions of this format, so a run of quick pairs is worth more than the same pairs spread thinly. That suggests a rhythm. When you spot three matches at once, take all three before hunting for a fourth. And when you find nothing, rotate instead of staring, because a rotation with a match at the end of it costs less than a long study of a face you have already read.
Read the far side without turning
Copy counting works here as well as on a flat board, and it is worth more because a third of the tiles are out of sight. Four of each design exist. If two are already cleared and a third is in front of you, the fourth is on a face you are not looking at and turning is justified. If three are visible, the pair is already in front of you. Even a rough tally saves rotations, and rotations are seconds off the clock.
Edges, corners and the tiles that go last
The awkward positions on a block are not the ones a flat layout teaches you to fear. A tile in the middle of a face has neighbours all around it and is still available, because the face itself counts as the exposed side. The difficult tiles are those pinned under a raised structure on the upper surface, and those in the inner core that only appear once a whole shell layer has gone. Clear the raised structures early: they are the only thing on a block that covers anything, and they behave much like a crown on a tall stacked layout.
The inner core deserves a warning of its own. Tiles there are not merely awkward to reach, they are unreachable until the shell around and above them has gone, so a design whose last two copies both sit in the core is on hold however much time remains. Copy counting is the only thing that tells you that early enough to do something about it.
When the block stalls
A rotating layout can run out of moves with a good number of tiles left, and the cause is the familiar one: two surviving copies of a design sit where neither can free the other, most often one resting directly on the other in a raised structure. On a block this is harder to catch, because the tile doing the blocking may be on a face you last looked at ninety seconds ago. Before deciding the board is finished, make one deliberate rotation with the raised structures in mind rather than the flat faces, and check each of them from two sides.
The same failure written out in full, together with the flat-board version of the diagnosis, is in why boards run out of moves.
Where to play it
The Dimensions layouts collect the rotating-block boards, with Mahjong Dark Dimensions as the timed original and 3D Mahjong as a slower way to get used to reading depth. Full screen is worth switching on for any of them, since the block is drawn small and the offsets that tell you which tile lies on top are only a few pixels deep. The wider framework, including the flat-board version of copy counting, is in the strategy pillar. A layout of that kind in the catalogue here is Mahjong Dimensions.
