Well theres alot to say....
...buts thats just cause its me reviewing it and not some normal person that isnt bored as hell. This is constructive suggestions only, so odds are you probably dont need to read this. Good game, but t could use MUCH more balancing and more effort put into the flow of the game (because one wrong investment or one right one can completely change the outcome of the game). especially because there is unlimited ammo but with low damage, isntead of purchasable ammo but with high damage. I would suggest a item shop that gradually expands with more balanced weapons rather than all items available at once where you can screw up investing in something too soon. Take away bloodlust and overkill but increase the average amount of points given per kill. as soon as one gets those upgrades its pretty much game over. make more upgrades, and make them stackable, but only for a selected group of weapons [it doesnt make sence if one upgraded every single weapon]. More units, lower enemy speed, bosses, armor, special weaponry [like grenades, flashes, defender turrets, tanks, etc] are all just more things that can be added. additional henchmen [using setable weapons and/or armor youve already bought] and upgradable barricades isnt a bad idea either. Well i suppose this is all i feel like thinking of at the moment, but theyre all possibilities for advancing the feel of this awesome zombie game. Just for one last suggestion, making a more interactive story line will definately help the excitement. the same area, doing the same thing can unfortunately get boring over time so dont be afraid to mix things up, but if you cant think of anything then dont worry about it, its all optional anyway (if you hadnt already guessed). please no complaints on how rediculously long this message is. I KNOW ITS HUGE, I HAVE NOTHING BETTER TO DO >:(