The adjacency bonuses are the interesting part, and they are also the thing most likely to go stale. Once players find one cluster that pays better than the others, a lot of auto battlers quietly become the same board every run.
Fixed boss days at 5, 10, 15 and 20 make that easier to solve too, because there is a known checkpoint to build toward instead of an unknown one.
So the thing I'd want to know as a player is whether the tile pool rotates enough that I can't just reassemble my favourite block every time. If it does, placement stays a puzzle. If it doesn't, it becomes setup I already know the answer to by the third run.
Good luck with the demo.