Very Nice.
Good game, exceptional if you consider it's your first.
Pros:
-Zombie game, with a storyline!
-Variety of weapons
-RPG Elements
-Decent Difficulty (First 5 levels)
-Nice Music
Cons:
-Needs a bit of balancing (Pistol Level 5=Headshot, gaurenteed)
-Number of Zombies/Zombie Difficulty (speed) needs to be increased.
-Pickups need to be reduced as game goes on.
-Music Toggle (Not just turn off)
As I said, a nice game, time to elaborate on some cons. The pistol is the infinite weapon. I only ran out of ammo for it once and I had an ammocrate anyways. At level 5 Pistol Skill the pistol always gets a headshot, thus no zombie ever lives. At about level 10 after I maxed all my items, I simply stood still aside from picking up some pistol ammo until level 20. At level 20 there were 5 Medkits 2 Ammokits 6 Shotgun ammo supplies 3 Clips for Rifle and 4 Grenades scattered around me.
My suggestion is to make zombies that possibly require more than 1 headshot, or to reduce the chance of headshot on the pistol. Also I turned the music off at one point because I heard the same song about 4 times. I could not turn it back on. That would be handy or a wider variety of songs.