Currently there are only two distinct squad member types.

This is the guy you start with and is equipped with a variety of tools to get around.

The Scout is present on just about every mission, and is currently the toughest combat ready class you have. Equipped with the grapple gun, the terra-scanner, demo charges, and rope n' nailgun means he's the guy who gets yelled at to do everything.

Generally you will start with the pistol, the grapple gun, and rope, along with some Scan Balls. This changes from mission to mission! Check your equipment list at the beginning. This can also give you an idea of how long the mission will be. If you have lots of supplies, brace yourself.

The Scout is who should go first in every situation since they can climb, grapple gun, and toss down ropes for hapless engineers. Speaking of which...

The Engineers don't have a grapple gun or even any traversal tools, which is why the first time they show up you are rescuing them with the Scout. They have a gun, but barely have enough ammo for two reloads on spawn.

Since their movement is so much more limited, the Scout has to help them out by making ziplines and tossing down ropes where necessary. The Scout should also be clearing out enemies in front of the Engineers!

The Engineers show up whenever puzzles are involved - they are the only ones who can drive vehicles and can remote control cranes and platforms which the Scout can't use. Solving their mobility problems and getting them to and from vehicles are generally how the puzzles are solved.

Vehicles can push each other but won't kill your teammates standing around. Beware, vehicles are finicky physics wise, especially when on moving platforms! When moving vehicles onto platforms, make sure you have the magnet on to reduce movement, or place it on a flat cave surface to prevent the platform from swinging wildly!

You control one guy at a time, and if you're playing on Normal and up, you have limited respawns when you inevitably die.

When you die and respawn, you appear on the nearest flat cave surface or base hallway, generally a floor up or down from where you fell down or with a tunnel between you and whatever killed you. Your previous body disappears which means the swarm of enemies that kills you spreads out, looking for food again.

The amount of respawns you have varies per mission and difficulty. The harder the difficulty you play on, the less chances you get. Difficulty also effects how many enemies spawn, but doesn't change damage or anything else. You die extremely quick in this game, and you can run completely out of ammo if you're not careful, so play accordingly.

You die instantly from falls or impacts at high speed. Falling more than twice your character's height instantly kills you. Slamming into cave walls too quickly instantly kills you.

Gravity and Physics are your worst enemies.

Monsters do a flat 20% health damage on sustained contact. Additionally there are radiation zones that drain your health as long as you are near. All of this together means - never get into melee range with enemies, or ignore the clicking of a geiger counter. You can easily find yourself getting two or three shotted by contact with a flier, contact with the worm it spits, and then a melee attack or contact damage from the flyer. Radiation saps your health so quickly that if you recklessly sprint in, you won't have enough health to get out.

Don't just rush back to where you were! The enemies that were clustered around your corpse have spread out now. Shoot some walls near where you ran in last time to draw out opponents. Give it a second and listen for skittering or the buzzing of flying enemies. If you got chomped by a ceiling monster, make sure you have a full magazine, aim at where it is and be ready for its emergence before falling back and rapid firing.

Get used to this. Your hopelessly fragile meat body is no match for the cyclopean stone you'll smash yourself into. As much as possible, keep your grapple gun aimed vertically to avoid getting literally carried away by momentum into a wall at fatal speeds.

If you run out of extra men, you fail the mission and have to start over! If this sounds like it'll infuriate you, consider lower difficulties. The later missions are no joke, and even if you know what's coming you can eat a lot of deaths from physics, swarms of fliers or forgetting about ceiling monsters!

If playing on a mode with limited respawns, SAVE YOUR MEDKITS FOR YOUR LAST MAN STANDING as they are incredibly rare.

To use a medkit if you have one, just hit 9 while standing up and you'll jab a syringe that heals 60% health into your thigh.

There are only two weapons currently, and no melee options. Ammo conservation is paramount, you can be forced to restart a mission if you are careless!

Yes, the basic pistol is the Desert Eagle, which chambers 16 rounds somehow. Despite being presented as a monstrous hand cannon, the pistol is actually your basic workhorse weapon that will do a majority of the killing in most situations. It might as well have been a 9mm since it's not an especially dramatic weapon.

All characters spawn with it, it can be used just about anywhere, and does respectable damage to all forms of enemies.

CHARACTERISTICS:
It's a semi auto with good accuracy and a laser sight. It can headshot flying enemies with a bit of luck, fire quickly enough to kill ceiling monsters, but seems to struggle with spiders and spider nests due to a lack of full auto and somewhat heavy recoil. It's incredibly useful in every combat situation since you can use it while using the grapple gun, or crawling.

Note that your aim is much worse when shooting while on a grapple gun rope. This can get you killed real quick if you're expecting to headshot fliers.

Also consider that you will be a huge ass target while dangling awkwardly in midair and you can't out run anything.

This weapon is your only option in a lot of situations, and will serve you well. It even reloads quickly. Just make sure you save a couple magazines when climbing or crawling into dangerous areas.

A 32 round mag and fully automatic fire makes this a good choice for clusters of fragile enemies. If you're struggling to kill a ceiling monster fast enough, this is what you want to be brandishing to give it a surprise. Only The Scout finds or wields this weapon. Mechanically speaking, nothing would stop an Engineer from using it, but on combat heavy missions you have only Scouts.

CHARACTERISTICS:
Fully automatic, also equipped with a laser sight, possibly weaker than the .50 cal, good long range accuracy and recoil control. Seems to be more of a DPS than a damage per shot weapon. Good choice for mowing down spider nests, or precision long range single shots. Eats ammo like crazy on fully automatic, and you will never, ever have enough ammo to feel fully comfortable. Reloads quickly, but can't be used one-handed.

I don't have a numerical stat list to show you, but this weapon seems to be more stable than the pistol, especially with rapid fire shots. I would say it's more accurate overall but its main improvement over the pistol is putting multiple shots on target.

Because you can't use this one handed, always make sure you never use up all your pistol ammo if you want to use a gun while climbing or crawling.

That said, on later missions, always be sure to leave a few reloads in the rifle to kill a room full of spider eggs - The eggs spawn around 5 spiders, and you will be hopelessly overwhelmed if you don't destroy at least some of the eggs quickly!

I swear this thing works better on the spiders than the pistol, if only because you can't critically hit spiders. Mowing them down in hails of lead is the only current solution.

No weapons can be used underwater at the time of writing, nor do they need to be... yet.

A gun that shoots a grappling hook and lets you climb and descend on a motorized harness. The Scout's favorite and most hated piece of equipment, this thing will save your life as much as it kills you. Has no offensive merit but is your main traversal tool much of the time.

CHARACTERISTICS:
Has a laser sight and, whenever equipped, zooms your vision ahead for you to see possible places to hook onto. You have unlimited ammo and ropes, and there don't seem to be any surfaces that you can't grapple onto. The grapple has considerable range, but if you can't see a surface when your vision is extended, you're unlikely to be able to grapple successfully. If the rope shoots out completely, as in leaves the grapple gun, you are out of range. The rope has to still be connected to the grapple gun to work.

Also consider the angle of the shot when using! Your shot can bounce off if you're too shallow. Even if you successfully hook onto something, you should still think carefully about what angle the rope is at before you swing.

You will kill yourself many, many times by swinging heedlessly into hard stone.

Your character's facing also seems to matter. When swinging, your character will try to brace for impact with their legs if you have them facing the wall, but they'll smash their head and die if you send them swinging backwards! Again, I don't have the numbers but facing the direction of the wall you're swinging to seems safer.

THE SOUND OF THE GRAPPLE HOOK HITTING THE WALL ALERTS ENEMIES. Beware of fliers.

You can also use this as a makeshift pair of binoculars to scout ahead since it automatically focuses your vision as far as it can go. Good for scouting for danger and enemies.

The alternate use of the Grapple Gun, less likely to kill you but gets tripped up by rope and requires you to hold the direction you need to zip in.

Since the zipline is motorized, feel free to defy physics and zip all over the place if you can manage it!

Be very careful using it with ropes hanging nearby. The game seems to be a bit confused at what you're trying to do if a vertical rope and zipline cord overlap and can result in spontaneous free falling.

When in doubt, hold the movement keys in the direction you're trying to go.

This is a highly situational tool that you don't really have to use unless you are in a puzzle about bringing Engineers someplace. Still, it can be useful for vertical traversal even by a Scout's lonesome.

CHARACTERISTICS:
Only the Scout has this tool, as it's intended to help other characters traverse and climb up terrain. The Scout takes out a rope, nailguns it into rock, and throws the rope forward. You can't aim it, and if you try to use this on a narrow vertical passage like a base's ladderway, the rope gets stuck up top, resulting in some amazing physics if you try to climb it anyways.

Obviously this has limited use - it's a simple rope that only goes up and down. However, the length of the rope is considerably longer than the zipline or grapple gun, and careful use can help you recover your progress if you have the great misfortune to die on a zipline in a very tall, empty room with nowhere to respawn halfway up. Stand a few steps back from a cliff, hold the Toss Rope key, and with some luck, you can find your way back up the next time you hurl yourself into a wall at mach 50.

You have unlimited ropes, but you can only nail rope to a flat surface. You have to be in just the right spot, and crooked angle floors don't seem to work.

I'm bunching these two together since you frequently only use one after the other. Only useful for puzzle solving and navigation, worthless for fighting.

CHARACTERISTICS:
There aren't too many hidden caves, but if a lot of rooms with flat floors seem to lead nowhere, you should investigate with the Terra-scanner. Using it is simple.

Select it or use the shortcut key to ready it, hold down the trigger and get a Spelunker's Ultrasound. If you do find a hidden cave, it's not added to the mini-map, and your explosives only reach down to the second tick on the scanner.

Demo charges can't be aimed, or thrown in any offensive method, which is truly disappointing. Your character sets the charge, places it on the floor and about three seconds later the charge blows a hole roughly two character lengths into the ground. You can use the charges anywhere, but it only seems to be effective on rock.

It has no effect on enemies, and you can't cheat by dropping a charge and ziplining away quickly to skip parts of a level. The charge will always go off as you are hooking up the grapple rope.

God knows I've tried.

Your best friend, bar none. Fills out your minimap, can open doors and use switches, can kill clusters of enemies, and looks cool doing it.

CHARACTERISTICS:
The Scout's best bud, the only downside to this thing is its pitiful battery life and the limited amount you can carry. To use it, just select it and you gently drop it into the air and fly it with the movement keys.

It can go quite far if you don't use any abilities, and it can go through small cracks and gaps in doors or floors. If you're not sure what lies ahead, send this guy instead of your scout.

The battery life on these things are never, ever long enough no matter what you do. You get around 10 seconds of flight, 5 if you're using it for combat. Despite its high speed, the low battery means you can blow through your entire allotment in minutes.

The Scan Ball can shoot a short range tazer that electrocutes enemies at the expense of the Ball's battery life. It takes a couple seconds of sustained lightning to kill fliers, spiders, and worms. You'll get more bang for your buck on swarms.

Useless against spider nests, you'll need to shoot those. Only eggs react to the scan ball, not other enemies. The Scan Ball usually runs out of power immediately after 3 or so kills, so they don't need to. Make sure you only use a Scan Ball for one thing at a time! Explore or fight with it, not both. You don't have the battery.

The Scan Ball can also push buttons or switches, but it can't turn cranks or pull levers. At least one mission REQUIRES you to have a scan ball to go through a small passage near the end! You can screw yourself over very hard if you try to conserve ammo by using only Scan Balls to kill enemies.

Use it and trust it, but don't be overly reliant on it. You still need to most of the fighting yourself.

This thing isn't ever listed in your inventory, but on missions that involve swimming you either spawn with it or have to find these. You'll know you have it if you see a mask when you swim, or see a blue OXYGEN TANK meter at the bottom right as opposed to the bland brown O2 bar when you don't have one. There's not much to say - it helps you not die when under water. Don't waste the oxygen, there aren't randomly dropped tanks in the wild.

You'd think this thing would be pathetic. You'd think it would be harmless and squishable. You'd be wrong.

While incredibly slow, small, and pathetic looking, this thing can three shot you in a heartbeat. Does the 20% contact damage if you run into it AND leaps up at you at close range for around 50% damage. Two of them at your feet and biting at you means you're dead. Laughable when you're a room away, but deadly up close, especially if a flier pegs you in the face with one.

Dies in one shot, and is spat out as a weapon by fliers. Be cautious and keep your distance.

Imagine bats that burn like acid on contact and vomit out killer maggots and you have a good mental image of what these are.

The most common enemy encountered. It will bedevil you on every single mission, and dealing with them never stops being a problem, no matter if you're in a cramped base or the largest of caverns.

They do 20% damage when ramming into you, no special animation is shown. Much more distressing is their vomiting of a worm, usually when closing in. They rarely hit with it, especially if you're backing up, but this can get you killed if you ignore the worm or are getting backed into a corner.

You encounter these in two situations: Individuals, usually placed at the top or bottom of ladders and caverns, and swarms, which can be clustered together or spread out over a large room. Always try to draw some out by shooting a wall near where you think they'll pop up and listen for the screech. Alternatively, if you can spare a Scan Ball, and they're clustered together, you can just murder the lot of them effortlessly. Five is my personal best for most fliers in one Scan Ball.

Dies in three shots. Can be headshot, but this is tricky when they're charging in.

The .50 cal pistol is great for stragglers, but don't underestimate swarms and keep a full mag of the Assault Rifle handy when five or more run at you. You sprint faster than they fly, so you can give yourself enough space to reload if you keep a long hallway near.

Remember this guy from the trailer? Yeah, it's the barnacles from Half-Life, but they reach out and grab you for instant death now. Distinctive nests in the ceiling are your first and only warning.

These are instant death traps. They wait for you to get in range, extend from their hole in the ceiling, bite your head and kill you instantly. Once that's done your body is dragged into the ceiling. There is no recovery possible once it gets you.

Every time you see ammo just laying around randomly in a cave, every time there's just a key randomly sitting in a poorly lit area, every time your spidey sense tingles - immediately stop, draw and load your weapon, and examine the ceiling. If these are in the room they'll come from the distinctive grubby organic nests in the ceiling that you'll learn to recognize immediately.

There aren't too many of them, but they tend to be most deadly when you are most of the way through a mission and are worrying about other things. Especially deadly in poorly lit areas with the roof just out of sight.

Dies when roughly 4 or 5 sections of the worm-like body are shot. Rapid fire pistol shots will kill it quickly without much trouble. Walk forward just enough to trigger its appearance and back up while emptying your mag into it. Rifles kill it even faster.

Either you notice it and kill it with no trouble, or it eats you. Those are the only two outcomes. Not affected by Scan Ball tazers.

Imagine if a freshly butchered turkey suddenly sprouted spider legs and tried to stab you with a three foot long spiked tentacle. That's the spiders in this game.

They move faster than worms but not as fast as charging fliers. They run at you once they notice you and hop at you to throw off your aim.

Once these start showing up, know that their nests are not far behind and you'll need to start saving as much ammo as possible for dealing with egg clusters.

Does 20% contact damage, and additionally have a dodgeable but deadly spike stab that does approximately 50%.

They can be placed around the level, especially in caverns, or can be spawned from eggs.

Eggs shoot out one spider every couple seconds when you approach or shoot them, and spit out at least five or so spiders. If you shoot an egg in a nest full of them, get killed and waste time coming back, you very likely will not have enough ammo to finish the level in later missions and die in a tidal wave of undersea meat spiders.

Eggs are unaffected by Scan Ball tazers. You MUST shoot them.

Spiders take 3 shots and have no head or notable weak spot. It's just a blob on legs that wants to stab you.

Eggs are the most resilient enemy in the game, taking at least 10 shots to pop. They also spray acid on death, just in case you thought it was too easy to take care of. Again, keep some rifle mags handy!

SCAN BALLS TRIGGER THE EGGS HATCHING, don't get suckered into chasing some fliers and setting off a mob of spiders! If you see the eggs but still want to kill fliers, shoot walls near you and not the eggs, lure the fliers out, and only go in with full pistol and rifle mags.

• Always check your inventory at the beginning of a mission, and double check to see if you have any other members of your squad. Squad composition and inventory change mission to mission and can make a huge difference in terms of how you approach a level.
  
  
• You generally always start with a Scout, who should be taking the lead. Keep Engineers back unless absolutely necessary since they are the only ones who can use vehicles and cranes.
  
  
• Don't trust the squad AI to do anything but run in a direction you give them! You should always clear out the path for squadmates you plan to have on the move.
  
  
• The Numpad switches between your squad quickly. At least one puzzle requires you to operate a switch, change characters, and then switch back. Be ready.
  
  
• Killing enemies is not strictly required. It is possible to trap enemies either behind doors, or under elevators, which saves you precious ammo and Scan Balls. Remember that as a Scout, you have many alternate traversal options and unlimited grappling gun hooks, so you don't need to use elevators if you don't want to.
  
  
• It's possible to fall and ragdoll and not die, if you crouch and crawl off a short cliff. This is completely pointless but looks funny. You still might just die even by falling a couple feet, beware.
  
  
• Environmental Hazards always have some kind of a warning. Either your geiger counter will go off, or there will be visual and audio feedback. You don't have to approach every single weird alien artefact. If one's in your way, check where your other squad members are, there's probably a puzzle involved.

The Plasma Cutter is rarely used. You use it to cut thin horizontal platforms in two levels, and in one level you need to find a "plasma charge" before you can use it. The plasma charge is just a pressurized bottle tank found in a storage room.

To cut through the necessary wall, you need to select it from the inventory - there's no shortcut key - and hold left click while standing on the left edge of the metal plate.

Your guy should cut through and the rest of the platform section should swing away, letting you by.

The jump button is not just a one and done button. As in Dying Light, you can hold it to get ready to grab and climb things. Also, the directional keys direct your character movement up slopes and over cliffs.

When making a sprint jump, HOLD JUMP and MOVE IN AN UPWARDS DIAGONAL TOWARD THE OTHER SIDE to improve your chances of catching and climbing the edge.

Holding upward diagonal directions can also help you sprint up cave slopes if you're struggling to run with only left or right inputs. You won't climb sheer walls - this isn't Skyrim - but you can save some time on grappling up and swinging over.

Frequently, missions require you to get back to where you started from. This can be gruelling, especially since enemies tend to spawn in the tunnels you ran through after an objective is complete.

However! With explosive charges, any elevator shaft can be a shortcut down to other levels. This works even if power is out.

If you need to get down to another part of a base, simply place the explosive next to the non-functioning elevator and blast an opening, and voila, you can now grapple your way down the shaft.

Stop snickering, please, this is quite serious.

Sadly you can't throw explosives up, or you'd be truly unstoppable, so this trick only works if you need to head DOWN to the exit.