I didn't have a problem with the quality, in fact it was probably better this way, but there were a lot of flaws.
1.) What is the purpose of jumping on the zombies? It gives you a combo score and thats it. It doesn't give you extra cash, it doesn't hurt the zombies in any way, and unless you've bought all of the accuracy upgrades, you'll die just by jumping on them, because shooting doesn't help.
2.)The health was a good improvement, but it made no significant difference because of the fact that it became so ridiculously expensive after the first two purchases. There should be separate options to buy health that increases or another that simply refills it. I understand that this is all to add a challenge aspect, but it isn't a challenge, it's not even possible. You'll just end up wasting your money.
3.) The weapons are not an upgrade, they're just different guns, which cost copious amounts of money to buy and upkeep with the price of bullets. The guns are no help.
4.) The body armor as well as the in game pickups are also not very helpful, you only get pick ups once in a blue moon and when you do, they aren't very helpful. The body armor doesn't prevent the amount of damage that it says it does, in fact I would like to question whether they actually do anything as well.
5.) The "implants" are a good idea as well, but not only are they too expensive, you are paying for nothing once again.
6.) The stages of zombies are a little ridiculous as well, they come nice and slow at the beginning, but before you know it, they are impossibly strong and come in numbers too great to be defeated, I think a more gradual and steady increase would make this game a little bit more "winnable" if you will.
Overall, the game was well made but had almost too many flaws to be enjoyed. Hopefully, with potential next games? you will take these suggestions into account.
`Anubis