The early experience feels very good. The idea is very innovative!!
The later levels feel a bit similar to me—mostly placing cubes and waiting for the right cards. The main difference seems to be just the map size or more obstacles.
I would love to see more new mechanics. Maybe you already have plans for this but haven’t implemented them yet.
One idea I can think of is having a more dynamic environment in the harder levels. For example, the map layout or environmental mechanics could change slightly each round, with enemies/magma/whatever moving along fixed paths. Players could also use blocks to stop or redirect enemies.