This is great, it feels somewhat vanilla, but in a good way, with some funky zombies to spice it up.
I do have one criticism. Be consistent with the amount of stats provided. I for example have no use for damage if you hide firerate. Its most obvious with the cool peashooter costume. It deals more damage at the cost of firerate and a cost increase. I can see the damage up, wich is great. However it is utterly worthless without knowing the firerate penalty.