I love the idea, and the graphics really help set the mood, it gives a Resident Evil vibe, which is nice. I like the sonar sound too, it feels weird for this game but it strengthens the mood.
The only downside is the control, the fact that you can’t aim while moving makes it hard to aim and dodge the zombies, making you force to take hits from the zombies while you shoot at them, and if would be a good addition to add some options to kill the zombies when you don’t have any ammos anymore.