Really neat game, I liked the atmosphere! There's one small bug that prevented me from moving on, though. After it attacks, sometimes the walking enemy will freeze in place. I ran out of ammo after shooting it once, and then it froze. Since the enemy didn't die and was blocking the way forward, I was unable to continue. :') I restarted the game and tested it again, and it doesn't seem to be caused by the lack of ammo (I shot it and waited, and sure enough, it froze).
Other than that, and a few of the points mentioned in the other comment, it seems like a really nice game. Good luck in the future! I think it would be exciting to see the game grow.
(here's an image of the frozen enemy when I tested it the second time)