Part of the reason Quake II and its different versions and Expansion Packs are so hard is the regular foes you get to find across the levels.
Quake II (core game)
- Parasites in general. A cybernetic quadrupedal creature that's Made of Iron, fast and stealthy, often appears at close range, and quickly drains your health with its unavoidable tentacle attack. When you hear it's footsteps nearby and you're low on health, you know you're about to get owned. Lord help you if two or more attack at once unless you're outside their attack range, in which case they'll send off the tentacle anyways, making them perfectly still targets.
- Gladiators are also Made of Iron, and have a hard-to-dodge railgun that chops off 50 health points.
- Gunners have to be respected in source ports (such as kmquake2) where they can actually aim their grenades vertically. A full grenade burst in the vanilla game isn't very dangerous since the fixed horizontal launch angle makes the grenades' trajectories predictable and easy to avoid, but in said ports you'll come to find very quickly that when properly aimed, it's a huge burst of damage that comes with very little warning and is difficult to dodge.
- Mutants are Lightning Bruisers with a Deadly Lunge that can stunlock you to death with the recoil from their frantic claw slashes.
- When you play the game on Hard, even the game's common enemies become Demonic Spiders. Light, Shotgun and Machinegun Guards, Enforcers, Gunners and Berserkers attack much faster, rarely have to reload, and can duck your projectiles with uncanny skill. The game's larger enemies can almost rapid-fire their weapons, and are even more resistant to being stunned. Most notable are the Tanks, whose 3-shot blasters and rocket launchers now shoot constantly unless you break line of sight.
- Tank Commanders, sturdier than the already hard Tank and with harder-hitting attacks, are extremely common in the City unit. Some source ports replace them with the Tank, drastically lowering the overall difficulty of the unit.
Quake II: The Reckoning
- All Beta Class enemies. Finding one is a good way to know that you're in for a WORLD of hurt.
- The Beta Iron Maiden is not too different from the default model, except she has homing missiles. In a mixed firefight, they're a priority target.
- The Beta Brains has Hookshot-like tentacles that deal more damage than the original, have much longer range, and pull you in when they hit instead of sending you away, and an optic laser beam that can roast you inside your armor if you face it for over two seconds.
- The Beta Gladiator has MUCH higher health because of their Power Shield, a Phalanx Particle Cannon instead of the usual railgun (without the Gladiator's signature firing delay, too, and unlike the player it fires three mag slugs instead of two), and an extra painful clamp. In fact, the Beta Gladiator is tougher than the original game's Super Tank and you only found two of those, in separate locations to boot whereas the Beta Gladiator is possibly the third most common enemy in the final hub, only behind Gunners and Guards. The only saving graces are a) that it stands still while firing, making it a sitting duck of sorts, b) the three slugs are fired in a straight path instead of a spread formation like the player's Phalanx, making it easier to avoid (at least in non-hallway areas), and c) they drop more Mag Slugs than it takes to kill them.
- The regular enemies also got some upgrades, making them harder than in the original campaign:
- The pack's version of the Enforcer loses the warmup animation the original had, and attacks you instantly as if it was a Weapon Guard.
- The pack's version of the Tank fires rockets instantly instead of waiting until the turret is prepared and loaded (this after you found cover behind a wall from the already painful Blaster and Machinegun attacks), as if he were a Super Tank.
- The Weapon Guards introduced in the pack (Hyperblaster, Ripper and Laser) are relateively squishy but still have more armor than their more basic fellows, and their weapons can deal surprising amount of damage, especially the Laser Guard's. For the latter, corner peeking with the rocket launcher or railgun is definitely not overkill if you value your armor.
Quake II: Ground ZeroBetter get your pair of Double Damage and Quad Damage ready to use at the same time and learn their location with these damn foes.
- Like in The Reckoning, the Enforcer shoots you instantly instead of having a preparation animation.
- The stalkers are small arachnid robots which only shoot a blaster bolt but can attack you from either the floor or the ceiling, take two Railgun shots to destroy, and can jump over any non hitscan attacknote . Have fun battling a bunch of them with the Black Widow Guardian spawning them constantly; the Invulnerability and Quad/Double Damage items that she's immune to are still invaluable to mop them up.
- Take the Icarus, an already annoying (yet somewhat easy to take down) flying enemy of vanilla Quake II which shoots a bunch of bolts at you, add extra health and a Power Shield to it, make it a common enemy on par with the already annoying Flyers, and you get the appropriately named Daedalus. If there's one reason to use the ETF rifle, it's this dude.
- The turrets, the Blaster turret in particular. For one, they're far too tough - you need at least three rockets or two railgun slugs to destroy one. Secondly, their projectiles hurt (the Blaster turret, the weakest of the three variants, hits for a ridiculous 20 points of damage!), they fire twice as fast as a stationary Gladiator, and save for the Railgun turret, they can Lead the Target. Number three, deployed ones are completely silent when not firing, so you'll only know one is around after they've fired, and by then there's no way to dodge. And worst of all, they are EVERYWHERE, to the point where they break the regular gameplay flow and force the player on a Pixel Hunt if they want to stay alive. Taking these bastards out is a chore more than anything, and it severely detracts from the expansion pack's enjoyment.
- And if you are annoyed at the turret, allow us to introduce you to the game's number one Elite Mook: the Medic Commander. Stronger and sturdier than the already annoying Medic, with an upgraded laser attack, and most importantly the ability to summon other enemy classes to the battlefield, ranging from Weapon Guards to Gunners to other Medics. If there's a huge bunch of enemies around, make no mistake, there's one around and you need to clear him with a BFG shot before the summoned Strogg outgun you. Some source ports replace the Medic Commanders with regular Medics, highly reducing the difficulty of the levels those are in and showing you how bastardly difficult they are.
- The PSX version of II has an exclusive near-literal demonic spider, the Arachnid, who has dual railguns.