I think "nothing too new or special" really fits this well.
The movement speed doesn't seem to change movement speed that much, but what really irks me is that upgrading the damage is required if you want to keep one-hit-kills. It was interesting at first, It made me realized on Day 2 that enemies would keep getting stronger. But then I had two-shot kills for several days, until suddenly I had to attack enemies that had NO health in their bar. I'd change that if I were you, so that graphically, the enemy's health bar is sectioned into however many hitpoints they have (at that point).
There is no way to heal your barricade (which is fine, makes it more "intense"), and you do get to shoot different enemies (after like, Six days. What's the hold up?). Actually, it wasn't until the machine-gunners shot me that I found out my barricade even HAD health. I thought it was just a game of keep-away.
Where is the music from?
Are the costumes historically accurate?
I'm giving you this extra half-star because when the enemies die, they fall down at different angles, and I think that's pretty cool.