I seem to be winning this game with ease, so if anybody's stuck or dont know which guns to use etc. feel free to use this little guide to your advantage. I don't think my guide is perfect, so if anybody has any better sugestions, comments etc. post here.

To start of, in the beginning of the game it's pretty easy to win the missions, I would save up the money to buy the magnum, and for perks I would buy the pistol master(very good skill) and laser sights to increase accurancy.
For upgrades I would suggest not buying armor alot since I personally think you don't need it that much, instead I would suggest getting damage, then either speed or reload, then luck.
also at the beginning save up money for the p90 as your primary and magnum as your secondary since they are perfect combination of power, mobility, price and rate of fire, dont buy abilities since I don't see any point in wasting money on them yet, same goes for perks, youre set until later levels.

If you're stuck at later levels were things get a little tough. and dont know which guns to use, I would like to mention a good set I've been using,

which would include the magnum with the teleport ability, good for avoiding alot of enemies later on since they are going to overcrowd you, for perk 1 which is necessary to have with the magnum is the pistol master which gives your overpowered magnum even more power and half the reload rate, so if you up the reload time a bit, it will seem like you have infinite ammo on your magnum. for the second perk I suggest either the laser sights (not really needed), deadly crosshair (doesnt help that much later on), extended mags(if you up the reload time and you have a magnum this will render useless), stealth(for lower missions, later on this will also prove useless), ability reagen(good for teleport ability if uou spam them alot) and health reagen(seems almost inevitable in the last couple of levels),
and for perk 3 I suggest either fast shot(I dont suggest using this), Critical master or Piercing bullets (recommended). The magnum in my opinion is the best weapon with one flaw, which is rate of fire, otherwhise perfect secondary weapon.

with the OP magnum and the starter p90, all the other guns would be a waste to buy, I suggest to save up until the vulcan cannon or the 'minigun' and then wreck shop. Also, if you're planning on using the minigun alot, another perk, deadly shield, would be a good thing with the minigun since the minigun hurts your mobility alot, on later levels it would be impossible to win without some speed.

Thats it, Hope it helped. Like I mentioned earlier, if you have any better ideas feel free to post here.

In response:
The magnum in reality is good for only so long as it has a pretty bad rate of fire and can only kill one zombie at a time with critical. The 2 shotguns are infinitely better when it comes to up close, and if you are the cautious type, get a sniper. As for my dream team of weapons, I carry the vulcan and the bfg. I have maxed out all the upgrades and beaten the last level on all difficulties. The best ability is pushback due to the fact that you have a lot of them and maybe the most important perk is piercing bullets (good for crowded levels). Though it may seem tempting, the assault master perk isn't worth it because by then you will probably have a better weapon. This game was awesome and I urge to make a second one with more shotguns, a grenade launcher, and a flamethrower. A la fin to the max.

You guys might be thinking ive gone mad but when i saw it hacked i played it and i cant...

...even find the first 3 zombies :(