would be better if...
1. put up a upgrade menu instead of collecting power ups.
2. less repeated areas (people get bored fighting in same look like area for 2 long)
3. better shooting ways
4. and finally- ammunition stock up so you don't need to find ammo every time you use special weapons.
room for improvement.
The thing that killed this game for me was that the aim was fixed instead of free moving. You could only shoot in 8 directions instead of all the ones you needed. I'm no programmer but this seems like a 4-year-old could fix this and make a world full of difference.
-.-
nothing special... but solid gameplay
Eh.
It was fun at first, but by level 4 it started to feel like a chore, and I was playing on the highest difficulty setting. You boast 10+ different weapons, but I don't really think that's enough here. 20+ might be more like it, but that's just speculation because I only managed to unlock one of them.
Game might have more lasting interest if the weapons didn't have to be unlocked (or if they were unlocked much quicker), if you could perhaps hold two or three weapons at once (allowing for more strategy), and if the levels were more varied (like maybe including interactive stuff, hazards, different terrain types...).
Also, nice coding. My computer is really slow and I didn't even get any lag at all even when the zombies were mobbing me.
So then
360 rotation. If other shooters can have it, so can yours. This game is essentially unplayable as it is. The gun you have is too weak or too slow, since on normal mode, the zombies take at least three shots to bring down, must be in one of eight lanes of fire, and are surrounded by 20 more zombies.
There is also no good way to kite the things either. The maps are just too small and much of the edges gets blocked by ponds and gravestones or whatever.
An easy step to improve the game would be to remove the weapon upgrade boxes and just make a point expenditure system to buy better weapons or upgrade the one you have for more damage and speed.