This was so fun! It's kinda easy to get overpowered, I didn't keep going because I was easily winning every day, but that can be fixed with some balance adjustments, the game loop is really fun and the different buildings are so cool, maybe you could have also added some different enemy types. Also the grave building and burying can get a little tedious.
Overall I had a lot of fun with this game and just wanted to keep playing, the game loop is so cool and killing zombies is very satisying.