Nice concept!  I appreciate how the first part of the game naturally shows you all of the game mechanics before the real game starts.  Throughout my playthrough, I noticed that stacking the snowballs felt pretty buggy most of the time so it was difficult to get the game started.  I also think that the monster moves a bit too fast for you to make decent progress.  Other than that, nice work!

Mostly a well executed game! Letting the player build their first snowman without any threats is a great way to let the player learn the mechanics comfortably before throwing them into the deep end.

The lack of BGM actually adds to the horror vibe of the game.

My only point of critique is there's not much indication whether dropping an item will cause it to get stacked/activated as opposed to just plopped down somewhere. This is a problem when you're trying to stack snowballs and putting a snowball down instead drops it on your location, nearly pushing you into the hat.
Some better indication on whether snowballs are stacked would also be good, I spent some time not realizing that a given snowball was already stacked and not behind the rest of the two.

Love it! Can be a bit awkward to stack things, wasn't quite sure if I was doing something wrong or it just wasn't working. UI might help there, if it's about dropping in a specific area.