Awesome game!
Really good concept and feels pretty complete - good audio, background music is cool. The decreasing healthbar is really cool, especially with the colour changes as the health hits certain limits. The starting screen and game over screen are a nice touch too!
I like the sprites you chose and the player animation looks pretty good :)
I'm curious how the score is calculated, on one playthrough I got a score of 220 with 102 enemy kills.
I love that the enemies appear to track you when you enter a certain radius - from afar their movement seems pseudorandom, but when I got close enough to them they appear to hone in on my position. If that is the case and isn't just my imagination, then great job on that! Such a neat detail that I'm sure was a challenge to implement!
Some feedback: similar advice I gave to another group - since we can't shoot + move at the same time (at least not at a quick pace) tweaking the player movement speed to be a tiny bit faster would help. The "room" is quite large for the size of our sprite and it takes a bit to get across when I have that last zombie to kill!
I'm also curious if the reloads affect your score (the lesser amount of reloads you perform in a round, the better). If it doesn't currently that might be a neat feature to think about in the future!
Big congrats to you guys for creating this fun game!