By far the most frequently encountered are the Common Ridden: basic shambling zombies who’re easy enough to despatch as long as you don’t allow too many to build up at once. They will occasionally show up in armoured variants (infected riot police, for example), where going for headshots is likely the safest bet. More challenging are the grotesque, overpowered mutations who can roughly be divided into five categories. The fast-paced, four armed Stingers will have you twitchily aiming at the rafters and dodging gluey projectile attacks. Massively bloated Reekers, some of whom explode on death, showering the surroundings with toxic pus, will have you emptying magazines into their swollen abdomens up to the very last second. Towering Tallboys cover ground quickly and cause big damage, requiring you to aim for the shoulder and detach their club-like oversized arm. Long-necked Snitchers will kick up a racket and call in the horde. Creepiest of all are the legless Sleepers, who appear dead but will spring out from cocoons in hidden corners to rip your face off in what’s surely a tribute to the sneaky Xenomorphs from Aliens. All have their highlighted weak points and its advisable to hit them as quickly as possible.
Then you’ve got the massive boss variants. We won’t spoil too many surprises here, but safe to say the first times you come across the hulking Breaker, tentacled Hag or the colossal ogre slinging projectiles like a living trebuchet, you’ll want to have a full sack of ammo to hand.