First of all it really needs an invert mouse setting. If its too early to make a menu for settings just make some button toggle the option please.
The game seems to run okay though for some reason it pushes my gtx970 to the limit that the fans go fullspeed.
As for the gameplay I think you need to work on the basic loop. It's an fps with a lot of melee enemies that you can't kill as fast as they come and it leads you to backpedaling a lot or at least I found myself doing that a lot. I'd like to see a melee attack of some sort. The ability to carry more than one weapon would be great too, even just having two would make a huge difference. I also didn't really like how little time drops remain on the ground. It's hard to make sure you get to pick up everything in time when you're running from a horde of monsters.
As for the forest you might want to consider somehow arranging the area into a map instead of such a huge open area. I feel like it could give the player a better sense of direction that they're going somewhere instead of just looking at the map for objectives.
I think it's a solid start. I look forward to seeing more of it.