An array of droppers in the ceiling drop "snow" (bonemeal) above the buildings. Each roof of the building contains a collection system, which sends the snow back up a bubble elevator to be distributed back into the dropper array.
There's noteblock music that plays as the snow falls as well. It's adorable. <3
If you're interested in any particular part, I have a timestamped YouTube video of this build on my channel.
I also play "Pig-Man" in this video, a mini-game built by RandyBishop (he's previously posted images of the game here on r/Minecraftbuilds if you wanted to check out any of the game play!)
Happy holidays!
by samazonrex