Cool game! I like the different enemy types and the mechanic of having HP and an Infection meter being different, giving you a chance to keep playing for more if you find a medkit but also not allowing you to constantly get hit.
What I had some trouble with is the shooting. I think it's confusing because of the different angles the elements of the game are. You can see the player's body but you can only see the zombies from the top. I also think it would be nice to be able to move and shoot in different directions.
It would also be nice to make the hitboxes of some zombies bigger and reduce a little the player hitbox.
Last, I feel that all the zombies are a little too speedy, it's nice that you included zombies that are faster but every zombie is faster than the player.
I can definetly see this game becoming even greater with some adjustments, like more maps, more enemy types and much more! Great job!