The idea seems interesting, but the execution need a lot of polish.
First the game start with this:
, it’s dark and empty, I though that some bug occurred and restarted the game for several times before seeing some zombies wandering.
Second there are no hints of what items you have to drop, what are they doing and when you can and cannot drop them.
Third when you failed the shift, it seems like there is no chance to restart the game, so again I had to restart the page.
Fourth - the UI is tiny, it’s also not properly stylized, but this is the minor issue, while unreadable UI is a major one.
I see a lot of constructive feedback here, hope it will help you to recognize weak points of the game and improve.
Cheers and good luck!