Wow, I can see you put in a lot of effort into this project.
I like the apocalyptic theme of the game, and the fact that resources are in the form of wreckage, it feels quite thematic.
The UI presentation is especially impressive, looks quite professional. I also like the idea of having to hunker down regularly to avoid certain death, making for a tense combat with a timer.
There are some minor issues:
The game is not optimized very well, it frequently lags and go under 40 FPS. Since you used Unity, I recommend using the Unity Profiler to try to diagnose and improve the lag, if possible.
The zombies infecting the units is very frustrating as the units essentially get killed in one shot very early in the game. I think the zombies should be nerfed...like having a chance to infect. (instead of guaranteeing infecting and making your units useless immediately.)
Also, there are some control issues, like the "A" move attack button does not seem to work, soldiers' attack movement is somewhat janky, and workers sometimes get stuck when building? Fortunately, most of the other controls seem to be working well.
All in all, a solid looking prototype/alpha game, with some polish, it could be a decent game. (Who knows, maybe you can overthrow Blizzard lol XD)