Hi,
Well, it was a long time, but I was able to get to the shotgun :D. Of course, I also got a gun :). But when I maxed out the bat, it was the easiest to attack with, since the attack radius is half a circle, the pistol reaches far, the shotgun might combine that, but I'm already tired of playing so much for check it :).
What I noticed is that you can attack through walls (green squares), but they block your movement, you can cheat on this, choose a position where there is a wall between you and the animals, but you can attack them :).
The statistics window is cool, but it would be good to guide the player through the first steps, highlight what can be upgraded, etc., since it's not immediately obvious that there are buttons for this.
A cooperative mode or multiplayer would be a great addition in my opinion.
It was interesting and fun, congratulations!