These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Game Breaker: You purchase weapons when you save up enough for them. However, there's nothing stopping you from skipping updating a few days and then buying the Holy Gun, which will erase everything onscreen instantly until the month is half-over. Then you can upgrade...
Goddamned Bats: By the time you get past day 20, everything. But helmeted zombies are the worst.
Scrappy Mechanic: Getting grappled by zombies plunges your health to nothing lickety-quick. It's also easy to accidentally get grappled if a zombie sneaks up on you. Incidentally, this only happens in the Xbox version. Thanks a lot, Press Start!