Guide: Surviving a Zombie Attack

So, you're in a room full of zombies. What now? First, figure out what zombies you're up against.
 * 1) Fast Zombies: Best dispatched with 2 or 3 headshots. If they are at the back of a big group, wait until they are at the front before shooting. Expert strategy: if you can close the distance and avoid/interrupt the first lunging bite, you can stunlock them with melee and they can't fight back as long as you keep your strikes fast and close. This is generally not recommended in crowd situations, though.
 * 2) Slow Zombies: If possible, use melee to kill them. The best tactic is to punch them, then run away until you can repeat. It usually takes a few hits, but it conserves ammo for Fast Zombies.
 * 3) Armored Zombies: The fastest method is a punch followed by a headshot. Also can be killed by shooting his legs. If you are out of ammo, simply punch him multiple times.
 * 4) Fire Zombies: Get as far away as possible before shooting. The explosion can take more than 2 thirds of your health, so make sure you don't use melee. If he is in a group, killing him will also blow up most zombies near him (although this is still not enough to kill some of them in one hit). Do not try to deck it with a thrown object while it's chasing you because half the time the resulting explosion will still hit you. If you can get far enough away from it before it sees you before igniting, you can usually outrun them if you have the space to run, so it's generally a good idea to keep your escape options open during clearing spaces, in case you suddenly need them.
 * 5) Tentacle/Hair Zombies: You can usually stunlock them safely if you mash the melee button after they cling to you, but if you're that worried about it (or if they happen to be in a group), shooting them is probably your best option.
 * 6) Huge Zombies: A fully charged melee attack is not enough to kill them, so make sure you have a few rounds spare. Other than that, melee all the way.

Now you know how to kill each type of zombie. However, there are some tactics that are universal, such as:
 * 1) Laddering: Stay on a ladder, shoot the zombies, then climb up a little. As long as your feet are above their heads, they won't notice you. Just wait until they've gone away and repeat. Expert strategy: you can also use laddering to punch zombies if they are close enough, because they can't hit you as long as you scoot out of their aggro range right after. NOTE: This only works with ladders pointing towards you, the player. Ladders pointing to the side will force you to climb defenseless.
 * 2) Fire Bombing: If a Fire Zombie is present, shoot him and run away as fast as you can. He'll then explode and kill all Zombies near him. As long as there's a floor between you and them, you'll be safe, so try to find a ladder to duck down before he gets you. This will NOT work if you can't fully get to another floor because it's blocked by a trapdoor or something, so don't try it. Extra risky strat: if he's near a ladder that goes to another floor, you can pop in and shoot or smack him in the kneecaps, then duck back out before they manage to catch you.
 * 3) Peeping: If you smash a window from outside a room, you will get full visibility of the room. Sometimes this will warn you about enemies inside and even give you an opportunity to pick them off from a distance, should that appear to be useful.