Cool entry!
Gameplay wise, I gotta be honest, I didn't get past the guards and gun bit. At first I was very confused because the text in the webGL version cuts off at the edge of the screen so I couldn't read it. Then I picked up the gun and it looks like I had to beat a ton of guards that have a lot of health, so I tried to run past but died. That was my quit moment. In my case, I think you could solve this by having a bit better tutorialization. I don't think you need to have all the text in the starting screen, you could have the relevant information in the level screen. For example, in the first level where you run from the zombies, you could have a "Find the gun!" prompt somewhere, and that'd be more effective in directing the player. Same goes for when you pick up the gun - "Defeat the guards!" somewhere on the screen. You can also make the difficulty scale a bit with time, so that you don't hit the player with a brick wall right at the start of the level (in the case of the guards, for instance). It looks like there's more cool content here, but I didn't get to see it! :(
I'm not sure if there was a connection to the theme.
Aesthetically, I think the game works pretty well, although some assets seem a bit disparate. I would recommend to add some sort of delay to the zombies' running animation. They look kind of unnatural because they all run using the same animation at the same time, so they look completely in sync.
The webGL version didn't have audio for me, so I can't really give you feedback here either.
Cool entry, keep up the good work!