I would have been pumped if this was a full game. It was a very simple concept, but with the addition of more weapons and levels this would be great.
~ Errors/Glitches ~
Maybe I did something wrong on my end, but when I had enough points I purchased the shotgun in the store. No matter what I did I couldn't change my weapon to the shotgun even though it was clearly unlocked on the screen. Was it maybe an error caused by me purchasing a weapon out of order? Because of this I can't truly give an honest review about the gameplay (see down below) because I don't know how those weapons helped/didn't help.
~ Animation/Graphics ~
I thought the graphics on the title screen were really well done and the character design was nice. I thought the level graphics was a bit basic, but it would make a really nice simple level one. It may be neat to have the zombies look like they're getting a little destroyed as you shoot them. Pieces falling off, etc... Maybe even the addition of some blood splatter on the ground and whatnot.
It would have been nice to have an animated health bar on the screen so we know exactly how many hits it's going to require before we die. Also, this would give us some physical sense of whether we are being hit by the enemy other than the screen shaking. It can be hard to detect a shaking of the screen if you are in mid jump.
Other than that the mechanics were really smooth and everything looked good.
~ Story/Gameplay ~
I have no clue what was going to be in your final version, but this has so much potential that I could talk and talk about it. I won't write that much this time because it doesn't seem to be something you're going to finish.
I think the addition of more weapons would be awesome. I had a glitch when trying to switch weapons so I don't know if the more powerful ones had any downfalls. Since the handgun had unlimited ammo, if the other weapons also had unlimited ammo the game would probably be way too easy. I got really far with just the handgun itself, I can't imagine blasting people with a shotgun while jumping around. Because of this error I can't comment on the weapons, power, difficulty, etc...
Maybe I didn't make it far enough, but different enemies and bosses would be awesome. If these were included please let me know and I'll try again so I can how they were. Also, after several waves it would be great if we went to a new map with a different background/obstacles.
Sometimes the enemies just spawn where you are standing. If you don't want to have them come from the sides you could try to have them crawl up from the ground or kind of get "teleported" in with a slight delay so we aren't caught off guard with a little bit of unfairness.
~ Audio ~
I usually comment on audio, but I'm being bad and taking a break at work.... well a mini lunch of sorts... I won't judge on audio this time around... sorry about that it kind of leaves a mediocre review, but I don't want to wait until I get home because I may forget what I was going to say.
~ Overall ~
If you do ever make this a complete functional game I'll be there to play it. With more variety in enemies, backgrounds, levels, and weapons along with the inclusion of newgrounds medals, I would think we have a winner here.