Looks cool already.
The gameplay of this looks pretty solid and I like how you actually crafted creative little encounters. The stealth, how you added cover and explosives as well as how you cleverly spawned the zombie as soon as the player reached that dead end, it all looked very fun to play. This is quite an achievment because usually when someone presents his first project, I for one, think it looks more like a chore.
So this is really a good start to a project I'll be keeping an eye on.
Now to what I find less decent: Its visually less appealing. The lack of shadows especially and you also use a lot of props that really don't blend together. I think investing some time in that aspect of the game, maybe learning how to modify textures to unify the look of the game would be a good idea. You also have things going on like trash cans stuck in geometry, random ww2 vehicles in a crassly different style in what is obviously a modernday themed game. I think this is an area where you can improve.
I've seen that you try to have this run on lower end systems. Here are 2 tricks to get more fps if you have not done this already:
1.Turn down "camera distance" in the TAB settings. You'll get a few FPS more and you can set it very low given your game being top-down view.
2. If you get into 3d modeling, try using modular terrain entities rather than the built in terrain feature. You can turn off the terrain while testing using F11 to get a glimpse at the instant FPS boost.
This is a tutorial for more things you can do if you are interested.
Good luck with your further developing!
-Wolf