The thing that differentiates your game from normal sokoban is the holes. Especially in the beginning there are a lot of levels that don't really take advantage of that. Later on, there are a couple of puzzle were you need to put blocks into holes so that you can unlock a new path, but only a couple before the snow levels start. I would have liked more puzzles about holes. Maybe some with holes that are traps, that you are not supposed to put the blocks into.
There is one of the snow levels that takes advange, but i totally understand that there are not a lot of them, the ones where i take advantage of the holes are the best levels of the game, but they were also the hardest to design and I didn't have much time since i had school.
Thanks for the great feedback!