Game also did not work for me in Firefox :
"Warning!
The following features required to run Godot projects on the Web are missing:
Cross Origin Isolation
SharedArrayBuffer"
Worked fine in Chrome. Game was quite fun to play, although is was at first not clear to me why my gun wasn't shooting. I thought it was reloading but I think it was that I was too close to a zombie and it was trying to use my knife instead.
Could have done with a kill count at game over instead of just restarting but overall: Good job !