By Slaanesh's crooked dong, people here seem to be way better at these kinds of games than I am.
I managed to reach wave 20 on Shack, mostly by cheesing it (open door and get an SMG asap, then hop on branch, shoot at Zombie heads while they climb up, once Zombies stop, hop down until the dogs turn up, climb back up and pick em off with the pea shooter) but the other levels just frustrate me, even on casual difficulty.
Cave is the worst, not the level itself, or the darkness, or the stupidly high price to turn the lights on, the bloody maggots are what's pissing me off.
So tiny they're hard to spot, especially while trying to shoot down the flies before they zip into your face, so tiny in fact that the wildly inaccurate starting pistol is simply inadequate to kill them before they jump and instantly grapple.
Either these fuckers need to be much bigger, or the first shot from your guns needs to go where you're aiming, at least when standing still.
The struggle on them also should be much easier, they're tiny maggots for fuck's sake, just brush em off.
Space Station and Jungle just swamp you with enemies before there's a chance to earn enough money to buy a proper gun and in FER the distance between ammo and health machine means you can't get both between waves.
So on wave 11, I just ran out of ammo for my guns and at that point the pewpew pistol just doesn't cut it anymore.