The Guards

The weakest and most abundant of all the enemies in Quake II are the guards. These processed humans come in three flavors: Light, Shotgun, and Machine Gun. Each of the three have their own strengths and weaknesses.

The Light Guards, with their red-colored uniforms, run around Stroggos equipped with a blaster weapon. They can’t do too much damage but they’re fast and annoying, plus they often travel in packs. They can be taken down with any of your arsenal up close or far away. Hit them first so they’re out of your face.

The Shotgun Guards are a bit tougher to deal with. These green-colored Strogg use an automatic scattergun as a weapon, which happens to be conveniently attached to their right arm. They will go down as easily as the Light Guards but they pack more of a punch up close due to their shotgun prosthetic. Save your ammo if you need to, and use your laser blaster to silence them from a distance. 

The Machine Guards are the strongest of the three guards. These black-chested soldiers use a machine gun to fill you up with holes at a distance or at arm’s reach. They also tend to travel in groups so watch for them at all corners hiding in a room. They are fast on the draw so bury these scumbags fast or before you know it you’ll be swiss cheese.

All guards know how to duck pretty well, so I suggest to aim low so you can peg them off in the legs. One trick you can use is to duck yourself, placing the muzzle of your weapon at their level without having to aim.

Enforcer

The Enforcer is one big, ugly dude with a chain gun for one arm. If you let him get close enough he can also slug you, so watch your distance. He’s pretty tough to knock down and he’s quite fast, so use a weapon like a machine gun or shotgun. When you see his arm raise, it’s time to strafe to one side if possible or plug him hard before he gets a chance to open fire.
Watch out, even if you blow his head off he still may fire a few uncontrollable rounds due to post-mortem spasms (like a chicken running around with its head cut off - yum!).
The Enforcers are pretty common in the first few units of the game. Remember you can also use the explosive containers to your benefit since the Enforcers like to hang around these objects for some reason.
Like the soldiers, the Enforcers are also capable of ducking your fire so aim for the legs if you want to guarantee damage.
All in all, the Enforcers shouldn’t cause you too much pain, but remember his chain gun can unleash a hailstorm of lead.

Gunner

These half-machine/half-human cyborgs are mighty and ruthless defenders of the Strogg empire. We’re talking double destruction here - one arm throws grenades in your direction while the other is a machine gun. How pleasant.
If you’re observant enough, you’ll notice it takes a moment to “open up” his right hand before firing. This is your cue to get the hell out of the way before you are toast. The Gunner is fast, and you can bet your life he’ll chase you around like a hungry wolf so use something powerful to hammer this beast. Try your chaingun, machine gun, or hyper blaster if you’ve got one, but grenades and rockets work great, as well.

Beserker
 
The flesh and metal brother to the Gunner - the Beserker - is a melee bad guy. He has two deadly arms, one is a spike and the other is a hammer. If you get too close, you ain’t walking home, cowboy.
The good news is that if you can keep your distance, he can’t hurt you since he has no ranged projectile. The bad news is he’s a really fast mutha so  either chuck grenades at him or blast him with rockets if you know what’s good for you.
You have to really careful while fighting the Beserker on higher platforms because one mighty swoop from his arms will send you flying. Not a good idea considering there could be lava, water with Barracuda sharks, or a spike trap below. Stay away and pummel the Beserker from a distance to avoid a disastrous scenario.
Oh…and one last thing. Don’t be fooled when you knock him down - keep watching because he’ll probably get up and begin the chase again. Definitely gib this sucker when given the opportunity.

Iron Maiden

The Iron Maiden is like Lara Croft on steroids and a really bad hangover. You just don’t want to go near these cybernetic Strogg babes; talk about implants!
The Iron Maiden appear later on in the game, characterized by their incessant moaning, so keep an ear open and you can probably guess when they’re around before seeing them.
On one of their arms is a built-in rocket launcher, while the other houses razor-sharp claws. It’s best to keep moving when you see them raise their arm or you’ll be decapitated or roasted faster than you can say “femme fatale”.
Expect to find two or three Iron Maiden traveling together. You’ll need something powerful such as a hyper blaster, grenade launcher, or rocket launcher to do the trick. 
The Iron Maiden are also really good about hiding in walls or under floors, so keep your ears open as much as your eyes are if you want to live long enough to see the Earth again.

Gladiator

Now we’re starting to get to the real meanies of this game. The Gladiator roams around Stroggos on two large mechanized legs and can blast you to bits with its shoulder-mounted rail-gun. The other arm is no better - huge claws capable of cutting you in half like hedge-clippers to a candle. 
The moment he turns and has you in his sights, it may be too late. Keep aware of his positioning and you’ll be okay. Practice the good ol’ strafe move since you’ve got a split-second to move if he’s looking your way.
The Gladiator is also the first Strogg where you will really need to start learning how to use the environment. The Gladiator is slow and bulky, so hide behind walls and tight places where he can’t get in. In order to take out this terror, you’ll have to shower him with grenades or plug him with rockets or a hyper blaster until he’s down for the count. If you’ve got a rail gun yourself, give him a taste of his own medicine and perforate him to your heart’s content.

Parasite

This four-legged Strogg likes to lurk in dark holes and corners of this planet. There’s a probe on his back that shoots out and attaches itself to you in order to suck the life out of you-- this weapon really hurts so take notice! He’s also pretty hard to knock down so keep a good few feet away from him to avoid his wrath, and use something major such as a hyper blaster, rail gun, or rocket launcher. If your aim is good and you don’t give up, you can put this beast to rest once and for all.  
Like the Iron Maiden, the Parasite loves to hide in the ceiling or behind unopened doors expect an uninvited guest to drop onto your lap before you know it. Surprise!

Medic

This creature has the ability to run around and heal damaged Strogg unless they’re totally gibbed. The Medic has some power of his own too - his hydraulic legs keep him quick on his toes while the laser blaster on his right arm boasts deadly accuracy.
There aren’t too many Medics found on Stroggos but because of their handy skill, they must be taken out immediately before they re-populate the premises. The best way to do that is to face him head on and blow him away using some serious weaponry like a hyper-blaster, rocket launcher, or even a rail gun.

Brains

This ain’t no cute nickname for the smarter Strogg of the bunch. This evil creature’s claim to fame is his life-sucking tentacles that protrude out of his chest while in combat. If you keep your distance, you’ll be just fine so tear him a new one from several feet away if you know what’s good for you. (Don’t underestimate his small head - he’s a keen fightin’ machine!)
Like the Medic, Brains aren’t found too often while you’re combing the Stroggos landscape but they’re around all right.

Barracuda Sharks

If you consider taking a small dip into the Strogg waters, you better clear the way first because many a Barracuda shark are hungry for some fresh human meat.
If you get close enough to notice the Barracuda shark’s sharp teeth or spiked-tail, then it’s probably too late. These indigenous nightmares are small and fast so aiming at them could be a problem. Feel free to use something that doesn’t require a lot of aim, such as a Super Shotgun, or predict their next move by studying their actions and make ‘em float with a rail gun, hyper blaster or rocket launcher. They also tend to travel in schools so watch your back, soldier.
It’s very easy to lose track of time while you’re concentrating on killing the Barracuda sharks so keep in mind that you’re underwater and come up for a breather as often as necessary.

Technician

This malevolent, robotic enemy silently hovers above your head. His metallic body is controlled by an organic brain that is preserved in a red casing in the center of its body. Enough blasts to the Technician and he’s done like dinner, but it may take a while. You see, the Technician is slow and proves to be an easy target, but this aerial beast can sure take a beating.
Don’t think he’s not packin’, either. The Technician uses three weapons - a shocking prod, a claw to tear you open with, and a laser blaster to top it all off.
Although you may see Technicians outside for the most part, tall hallways are also home to them. And remember they will follow you until the bitter death - yours or his.

Mutant

Thankfully, you won’t run into this flesh-tearing animal too often on Stroggos. This is the only organic creature on Stroggos, born out of the toxic waste flowing out of the populated industrial areas. If you run into the Mutant in knee-deep water or in damp caves, say your prayers and run because this mistake of nature is fast n’ fatal.
Any solid weapon would be ideal to use on the Mutants: rail gun, hyper blaster, Super Shotgun, grenades, rockets, or if you have lots of ammo - a machine gun or chaingun.

Flyer

Just like the Technician, the Flyers swarm above your head from the unfriendly skies and will stop at nothing to cancel your contract with life.
Flyers are very weak, but a few of their key features makes them tough competition: they’re extremely fast and agile, they usually travel in numbers of about three or four, and they can hit you with their laser blasters (built into each wing) from a good distance. Make sure not to use the shotgun on them since you’re accuracy is essential in winning battle. Also, don’t bother with something that takes a while to load or your wasting your time - they’ll move before you even squeeze the trigger (so the rocket launchers are out). Instead, attempt to destroy them with a chaingun, machine gun, or a hyper blaster.
The Flyers are as annoying as mosquitoes on a sticky summer day so keep your head up when possible and get ready to swat ‘em but good.

Icarus
 
The last of the flying Strogg race is the Icarus. These cyborgs use jet packs to soar the skies, plus large laser blasters on each side of their shoulders pave their way.  
The Icarus falls in-between the Flyer and the Technician since they are fairly tough to knock down and about medium on the scale for their dexterity. Once you’ve got one in focus, unleash your rockets, hyper blaster, or rail gun to spank the last nail in the coffin. When they fall to the ground and die, their fiery ashes will illuminate your surroundings,. a small visual award to confirm how much ass you can kick.

Tank, Tank Commander, and Super Tank

Witness the three levels of increasingly more difficult aliens to destroy.
The Tank and Tank Commander are bipedal metal machines capable of turning you into Strogg chow quite easily. While the Tank is found in multiple areas of the planet, the Tank Commanders are a special class used to protect the industrial areas from intruders. Both are equipped with an arm-mounted machine gun, an arm-mounted laser blaster, and a shoulder-mounted rocket launcher. The Super Tank is huge, larger-than-life tank that moves on treads very slowly around the outskirts of large, outside area. It, too, has rocket launchers mounted on the top portion of its torso.
In order to beat all Tanks, remember you are much quicker than them and milk your shots for all that they are worth because--they can take all kinds of abuse. Typically, I’ll find a small area to hide in where I can see a corner of its lower extremities and I’ll just keep hammering until it bursts into flames or falls to its knees. 
Use the best you got whether it’s a rocket launcher, grenades, a hyper blaster with lots of cells as ammo, a rail gun, or even the BFG10K if you can fire far enough away. I don’t suggest running head-on into a room with one of these killers - plan your attack strategy before-hand to avoid any unfortunate situations.
Note that there’s a second or two when their rockets will swivel around on the shoulder to match their view. You know it’s show time, so strafe out of the way or constantly circle them if you can.
Eventually, you will be victorious and you further gib them to pieces if you really want to.

Drone

This level boss will appear a couple more times throughout your journey on Stroggos - and the surrounding satellite on the secret level. The drone looks like a huge, flying bee, proficient enough to turn you into liquid honey in a matter of seconds. 
Like most level bosses, they’re big and powerful but slow as hell, so make sure to take advantage of this weakness. Its primary weapon is a set of five rockets tucked in under its body. Launched all at once, this is enough deadly force to demolish you instantaneously.
To kill the flying drone, just think of the Soul II Soul song “Keep On Movin’ “ because that you gotta do! Use the environment for cover such as hallways, pillars, and other protective areas so you’re not exposing yourself in the open. Select your best weapons and plug away. When you get a good angle, stick with it and fire rapidly - this way you may be able to stun your opponent long enough to finish the job.
With enough persistence, agility, and firepower, the drone will fly no more.

Makron

Jorg the Makron is the big cheese out of all of the Strogg. He’ll also be your last partner in the death dance at the conclusion of the single-player game.
Before you even see this giant all-mighty Strogg, you’re hear his thunderous footsteps…
The Makron is armed with a rapidly-firing chain gun and dual BFG cannons. You’ll be obliterated unless you’ve formulated a plan of attack here. Basically, there are many areas to hide so take good advantage of his sluggish means of transportation and use the very, very best you’ve salvaged as weapons. Whatever your choice for destruction - BFG, rail gun, hyper blaster, and so forth - just make sure you’ve got plenty of ammo readily available and don’t take your eyes of the Makron for a second or it’ll be too late (also remember to keep your “always run” option turned on!).
Just like with other tough bosses on Stroggos like the Super Tank or the flying Drone, you must find a soft spot on him and don’t let up. The best way to do this is slightly peer around from a pillar and aim at a leg until it realizes where you are. You will persevere after a while and the Makron will collapse into a pile of alien junk…but wait…there’s more!
Just when you think you’ve destroyed the Makron, a smaller Strogg will hop out and continue to fight. This funny-looking creature has a long snout shooting out depleted uranium slugs (like your rail gun), a BFG on each arm, and he sprays lasers at you to top it all off. You can either kill this durable little guy the same way as with the Makron (hide, shoot, hide, etc.), or if you time it right, you can knock him down, and when he jumps back up, hit again at a close range and he should fall back down again. If you get a good rhythm going, you can beat this creep but be forewarned - all you have to do is miss one shot or fall out of sync and you’ll dead meat (so save your game often)!
At last, when you’re tired, weathered and worn, you will split him in half and observe as his brain will fall out of his split skull… 
Cool! Feels good to save the Earth, huh? Good job, soldier!