Most people meet the block puzzle through its most famous ancestor, where pieces fall from the top of the screen and you spin them into place before they land. Rotation is so central to that experience that it is easy to assume it is part of the genre's definition.
It is not, and removing it produces a substantially different game. Block Blaster is a good place to see why: an eight-by-eight grid, pieces you drag on by hand, rows and columns that clear when full, and one restriction that changes everything. The pieces cannot be rotated. The shape you are dealt is the shape you must place.
What rotation was actually doing
In a game with rotation, a badly planned board is usually recoverable. An awkward gap can be filled by an L-piece turned the right way; a narrow column can take a vertical bar. Rotation is a general-purpose repair tool, and having one means you can play greedily, clear lines aggressively, and fix the mess afterwards.
Take it away and every gap you create becomes a commitment. A single empty square in the middle of a row can only be filled by a piece with a matching protrusion, in exactly one orientation, and if that piece never arrives, the square is dead for the rest of the game. It does not just block itself. It blocks the entire row, permanently.
So the skill shifts. Instead of how quickly can I fit this piece, the question becomes what does placing this piece do to my options three turns from now. That is a planning problem, not a dexterity one, which is why these games work perfectly well without a timer.
The strategy that follows
Once the constraint is clear, the correct play falls out of it, and it is the opposite of what most players do instinctively.
Protect one large open region. Survival in these games is not determined by how many lines you clear. It is determined by whether every piece you are dealt has somewhere to go. One preserved open area is worth more than three clever clears, because it guarantees that even the most awkward shape has a home.
Place the biggest piece first. When you hold several pieces, the large awkward one is the one most likely to become unplaceable. Fit it while you still have room and the small pieces will find gaps later. Do it the other way round and you will end a game holding a piece that fits nowhere.
Build from the edges inward. A gap against a wall can only be approached from one side. A gap in the middle can be approached from four. Keep the difficult geometry where it does the least damage.
Refuse clears that leave holes. This is the hardest habit to build, because a clear feels like progress. But a clear that strands one isolated empty square has traded a point now for a permanently damaged board later. Skip it.
The whole family
The same logic runs through a group of games that look unrelated on the surface.
TenTrix Block is the same shape of puzzle without a clock, which sounds like an easier game and is really an invitation. Because there is no time pressure, there is no excuse for a careless placement. Every loss is a planning error you could have prevented by looking at the board for another four seconds.
Sokoban Master takes the idea to its logical extreme. Crates can be pushed but never pulled, so a crate shoved into a corner is stuck there for good. A Sokoban level can become unsolvable twenty moves before it looks lost, and recognising that state is the actual skill. It is the purest expression of the same principle: the constraint is not what you can do, it is what you cannot undo.
Hexa Color Sort applies it to colour rather than shape. You sort hexagonal blocks by colour with a limited number of free spaces, and the standard failure is filling every free space with a different colour until nothing can move. Same trap, different clothes: spend your flexibility and the puzzle closes around you.
Why the constraint is the point
It would be easy to read all of this as games being needlessly restrictive. It is closer to the opposite.
A puzzle with a general-purpose repair tool asks you to execute. A puzzle without one asks you to think ahead, and thinking ahead is a more interesting thing to get better at. The reason these games survive without graphics, without a story and without a timer is that the constraint generates the depth all by itself.
The practical version, if you only remember one thing: the board you can still play on is worth more than the points you just scored. Almost every loss in this genre comes from getting that backwards.