I love your game, amazing idea and thanks to you I'll return to old beloved game, more on that later in the review. Well, nothing is perfect, even your amazing game, it has some bugs and you made few mistakes during development. Nothing major luckily.
Firstly, stones. The way they work seems very off and causes some unintentional behaviour to happen. Player character throws stone too low and to hit the enemy face Player have to look straight into the sky... or use them as landmines. You can easly beat the whole horde of enemies using three stones simply just by throwing them at the ground. I liked when rocks hit two or more enemies mid-air, it felt satisfying but I believe the landmines killed this feeling after I found it.
Leveling up also is broken. Because how throwing rocks work you can easly get multiple upgrades at the same time. You should destroy the rock if it hit the door. And picking the door to shoot feels wrong, it's just pure rng. Were I you, I would add some markers what each door has behind them. Like offensive, defensive and support door, each one of them have their own pool but Player knows what each door does and this simple changes helps take better decisions. Also pause menu and options menu is pure jank. It's very easy to open everything by mistake and kill the whole run.
Nontheless I enjoyed a lot your game! It remind be of good old Call of Duty Zombies. Training zombies and getting perk-a-colas is amazing idea to make a game around it and I think you did a really good job. If you put some more work into this project, add more enemies and add more permanent and temporary upgrades you will make amazing game and very engaging at the same time!
Good work and thanks for making this gem! Keep it up!