While there are several issues with this game there is one aspect of it that is done extremely well. Combat in this game is done with both aiming skill, target priority and very heavy emphesis on using crowd controlling shots from your guns. Most games have guns that do damage one way or another, this game has multiple guns where they have a fire mode dedicated to crowd control over damage. This is not only useful it is absolutely necessary, especially when playing on harder difficulties. The game really shines in situations that look hopeless, then just one or two things are used in right order and all of a sudden the player made it look like the encounter was a joke. This exhibits skill display, and this is why I'm writing this guide.

Few Basic tips that are applicable across all difficulties.

• Be mindful of your surrounding. This sounds silly but a lot of deaths will come from crap blowing up because you didn't notice what was close to you.
  
• Use that surrounding to kill enemies. Use your basic Machinegun and plasma to blow up cars, barrels, and other hazards.
  
• Small fast enemies take priority of big ones. Including gorillas, grenadiers, scarabs and so. They will swarm you, surround you, make it difficult to move around and kill you before you realize what happened. Controlling swarms of small enemies is key to most encounters.
  
• Basic gorillas are nearly harmless. All they do is stomp the ground when close, and charge at you otherwise. If there are cars and other stuff around they can kill themselves without you using much ammunition.
  
• While CC alt fires effect ALL enemies except bosses there are cases where their effect will be a second too late, for example mid charge if timed poorly. That leads to surprisingly amount of deaths.
  
• Never stand still when fighting enemies who use missles. This especially includes airborne enemies. They will be a threat when you are trying stick to a small area and shoot them. If you move and blast them on the move (railgun, smartgun, RPG with laser) they should be less of a problem.
  
• Avoid big scarabs. Focus fire them at first, then deal with small enemies until you have room to shoot them back. The little scarabs will kill you faster. But with right CC you can catch them all and deal enough aoe damage to kill the small ones and dent the big ones.
  
• Get REALLY comfortable with constantly switching gun modes and the two guns. Unless shooting stuff from afar, or using shotgun/plasma/machinegun to kill small enemies after you fire immediately switch to a different mode/gun to not waste time.
  
• Bosses themselves are easy, the adds are what make it problematic. First and second boss just require good skill versus groups, which you will learn (or die repeadetly). Last boss you just need to CC the small enemies in order to position yourself correctly. You will use gravity grenade, emp and stasis A LOT in that fight.
  
• Walk around with Smartgun equipped. (once you unlock it). Unless you have all spawns memorized, it will give you a second or two to switch to what is appropriate for the encounter.
  
• Use Smartgun and Railgun if behind cover if you are unsure of how to tackle a situation. It is a bit cheap and time consuming, but it can get you through a great deal of encounters. I would recommend being more agressive in almost every case, but this can work.
  
• Heroic mode is ♥♥♥♥♥♥♥♥. Partly because some encounters require near perfect execution and one small enemy can end up in restarting a mission. I would attempt this only when memorizing all enemy spawns, and even then there will be a lot of frustration involved.There are also some platforming bits that can end up in silly deaths.

My first run was hard. I had frustrating moments, and I had moments with a huge "aha" exclamations. Biggest issue I felt was learning how which gun is useful (and they ALL are, as I will go over in upgrade section). There is also some memorizing, because some enemy spawns can end up in quick death unless you react quickly enough.

1) Normal difficulty is well balanced experience. The damage you take is quite generous (in comparison to hard and above). But other than that you can still die quickly to mistakes (shooting environmental hazard, getting swarmed etc). For just enjoying this game without worrying about near perfect executions of some fights I would recommend playing this. I have extensive exprience with games like Serious Sam (where I can clear the whole game on Serious without getting hit), or Painkiller, or any build engine games, or Doom and its mods and so on. I recommend this difficulty when just wanting to hop in the game, and LEARN it. Use other difficulties when you are applying your knowledge.

2) Hard difficulty. The right balance between execution and enemy threat. Enemies hit hard, damn hard. Enemy HP is higher but not absurd bullet sponge like on insane. Your damage intake will skyrocket. One small enemy can kill you quickly if you don't react right away. The exploding ball guys will be the death of you a lot, so don't feel reserved about using a CC shot on them. Playing this difficulty first time is trial by fire. Knowledge in this game is just important as execution. Lack of will cause a great deal of trial and error frustration (partly why I'm writing this). Some guns become less useful, mainly assault rifle and plasma, but still useful against small enemies. You will be using grenades and explosives on medium enemies more often, but that isn't a huge shift.

3) Insane. I'm not a huge fan, not that it isn't difficult enough, but here it starts bordering on cheap. So many objects in maps, that even a small brush will end up in death. Very little room for error. Enemies have absurd amount of health. Grenadier or Scarab take forever to take down. Eating rocket after rocket, grenade after grenade and they keep coming and dish out absurd punishement. If this difficulty focused more on mechanics (more enemies, different attacks). Instead of just buffing enemy HP and increasing damage intake it would be more worth to play. It isn't impossible, it is just tedious and frustrating.

Whichever difficulty you chose the upgrade and tactics in this guide should apply.

Each gun has three points to invest in. First to unlock the basic weapon. Second for the alt fire and third for a passive upgrade. After unlocking the weapon, you can chose weather to get the upgrade or alt fire. It does not have to be in order. To unlock 4s and 5s. You need to spend a certain amount of nano on other upgrades. I recommend unlocking 2s and 3s for both guns, since they all have CC alt fire.

This weapon focuses on bullets and explosives. 1 and 2 are hitscan bullets, 3-5 are all explosives. Overall DPS this gun is better than N.R.G. but it also has less utility and most of it's damaging fire modes are projectiles.

1) Assault Rifle

• Primary Fire: shoots an automatic hitscan gun with average spread. (Priority: start with it)
  
• Secondary Upgrade: Gives a small zoom, this LOWERS spread. (Priority: low, but necessary for efficient use)
  
• Passive Upgrade: Increases rate of fire. (Priority: overall low, but MUST to make the gun useful)

Evaluation
It took me a great deal of fiddling to see if this gun is worth it or not. My conclusion was that it most certainly is. There is a catch though. It ABSOLUTELY needs the passive upgrade. Without the rate of fire increase the gun is too weak to use on anything other than small number of small enemies, and even in that case plasma and shotgun will outperform it. It's only use is blowing up environment without wasting ammunition. That is until you upgrade this fully. When fully upgraded this provides great utility to CLN gun. It will shred small enemies, it will even kill medium enemies quickly when zoomed in to minimize spread. If you can track and aim well you can clean groups without switching to something else. It is also good for finishing off gorillas or bigger enemies to not waste ammo, because this is hitscan. The catch lies is that you just can't afford to upgrade this over other guns. Other guns have a far bigger impact than small utility and ammo saving this offers. Even just one point in shotgun will deal with small swarming enemies, AND you get the EMP flachettes as alt to handle bigger things. So I wouldn't put points into this until other guns more crucial upgrades are acquired.

2) Combat Shotgun

• Primary Fire: Shoots a shotgun blast with very high spread. (Priority: High, get it after grenade launcher and mortar)
  
• Secondary Upgrade: EMP Fletchettes, shoots projectiles that immobilize enemies for few seconds if they hit (Priority: Medium-low. I would get this mid game. It isn't necessary, but nice to have later).
  
• Passive Upgrade: Shortens Reload time, meaning increases rate of fire. (Priority: medium. Get this before secondary. Since shotgun is useful when cornered this makes it even better, but it is still not high priority)

Evaluation
This thing is a one point wonder. Even just unlocking this has great use throughout the entire game. Damage output point blank is really good. This means it will serve great against small enemies in cramped areas. It will even killl medium enemies in few shots close up. The knockback innate to the blast is also very nice when dealing with swarms. It's other upgrades are great, but they aren't high priority. Even though this is the first CC alt fire, it is also the worst. Get it but later in the game when encounters start to become larger and you are fighting multiple enemy types at once. The rate of fire upgrade is wonderful. It makes it so that you can handle swarms of little enemies without anything but this. You don't need to switch, or use a CC. Now this will serve best if you can funnel enemies to you, if they are attacking from all sides, punch through using the shotgun and then switch to a different CC to handle to situation.

3) Grenade Launcher

• Primary Fire: shoots a gravity bound projectile that will bounce if anything by enemy is hit. Explodes on impact with enemy. (Priority: Absolute top. First thing you should get).
  
• Secondary Upgrade: shoots a gravity grenade that sucks ALL enemies in.(Priority: Absolute top. Second thing you should get)
  
• Passive Upgrade: Increases radius of it's projectiles. (Priority: medium-low)

Evaluation
This thing is absolute must if you want to handle this game well without punching your monitor. It is useful from the moment you get it to the very end of the game. Infact this gun is extremely useful in the final fight, Both fire modes are outstanding. Primary does good damage (though it will take some getting used to the projectile curve and velocity), the secondary is the best damage setup utility in the game. It will suck enemies so your blast from explosives will do damage to all of them. You can shoot your primary after your secondary, it will suck the grenade and explode doing damage to enemies. This is extremely useful against swarms of small enemies. Makes the encounter go from instant death to two click solution. Note that grenade will not suck in gorillas mid charge. The passive upgrade is nice, but it isn't necessary, because the gravity grenade is enough to suck everything in for it to be blasted with regular grenade. This gun is also used in conjuncton with other explosive weapons when bursting down gorillas and other big enemies. Switching between 3,4 and 5 for maximum damage output.

4) RPG

• Primary Fire: Shoots a rocket that explodes on impact. (Priority: Top. first thing to get out of all 4s and 5s)
  
• Secondary Upgrade: Laser that guides the rocket, like in Half-Life (Priority: medium-low. Get in mid to late game)
  
• Passive Upgrade: Launches cluster missles on impact. (Priority: high, get it after unlocking railgun)

Evaluation
This is the first thing to unlock out of all 4s and 5s. I deals outstanding damage, has a big splash radius and is applicable to nearly every encounter. This gun has no finesse or utility, it is straight up damage, the best of it and you will need it. Secondary upgrade is useful later in the game where flying enemies show up, or shooting things from afar. The passive upgrade is a must, since increases the damage of the rocket a great deal. The way I usually upgrade is I unlock this, then I unlock Railgun, then I take the passive for this. There is little strategy using this thing. You fire it, switch to something else while this is on cooldown and then switch back to it to fire again.

5) Proximity Mines

• Primary Fire: Shoots up to three sticky mines that pulse. If enemy is caught in the pulse they explode. They also stick onto enemies. (Priority: High-medium. not very useful by itself).
  
• Secondary Upgrade: lets you remotely detonate your mines, including mid air. (Priority: very high if you unlocked the weapon. Meaning get this immediately after unlocking it)
  
• Passive Upgrade: Lets you put out up to five mines. (Priority: low, don't bother untill you have nothing else to put points into)

Evaluation
I avoided this my first run, and that was a mistake. The problem with this gun is that it's primary fire is nearly worthless. Most of the time you don't have time to lay down traps, you can just shoot a rocket directly or any other means of damage. However secondary fire makes this gun extremely useful for every enemy. Air Burst mine will kill small and medium enemies quickly. Direct hits will do good damage even against big enemies. This will be used in with RPG and GL for maximum effect.

N.R.G. Weapon

Unlike the CLN this gun has less aoe capabilities and raw damage, but it makes up for it with utility with nearly every fire mode. This gun also has two modes that shoot through walls and cover, making it invaluable in nearly all situations. Both CC alt fires this gun offers will make the game far less aggrevating and easier to deal with.

1) Plasma Rifle

• Primary Fire: Rapid fire of small balls of plasma. (Priority: Start with it)
  
• Secondary Upgrade: charge up the weapon to shoot a big ball of plasma that explodes on impact. Higher charge does more damage and has higher aoe. (Priority: medium. Useful to grab even early game, in between some of the more necessary options.)
  
• Passive Upgrade: increases amount of projectiles in primary fire, meaning increases rate of fire for primary, reduces charge time for secondary and makes all plasma projectiles fly faster. (Priority: high-medium, if you want to use secondary with efficiency this is a high priority upgrade).

Evaluation
Primay fire is useful from the get go. If you predict and track well not to miss this will plow through small enemies and even deal decent damage to medium ones. With its passive upgrade it can be used for finishing stuff off like the Assault Rifle. The big thing about this gun is its secondary. It offers instant aoe damage. Like an energy rocket launcher. But the catch is the charge up time. Usually I recommend not going for lv 3 charge, and letting go after 2 for groups. For medium enemies charge 1 will suffice. This works extremely well with stasis and emp to clean our groups of small and medium enemies. It however needs both upgrades to be fully useful. I argue that this is worth getting, even early game, since it can be applicable all the way through. If you can fit the two points early to mid game, this with conjunction of the CC shots from blaster and mortar will clear out crowds without have to use CLN.

2) Shock Blaster

• Primary Fire: Shoots a wide arc of electricity short infront of you, shocking and doing damage. (Priority: Very High, but only because of it's alt)
  
• Secondary Upgrade: Blasts a 360 EMP wave in a decent radius around you, immobilizing enemies around you. (Priority: Top, as soon as you unlock the weapon, next point goes here)
  
• Passive Upgrade: increases the range and effect of both modes. (Priority: low, get it after everything else necessary)

Evaluation
The gun by itself offers some utility. It does ok damage per second and stops enemies when they are in the effect. In comparison to shotgun or other guns it falls flat. It will be useful to temporary stun things with primary to position yourself and switch to a different gun. The alt fire on the other hand is a must have. Stops everything in their tracks for few seconds letting you switch to a more damaging weapon and start thinning things out and get out of the way. It is absolutely one of the best setups for stronger hitting guns. Only downside is that you have to be close. But since a lot of fights end up just that you will get use from this from when you get it to the end of the game.

3) Electric Mortar

• Primary Fire: Shoots a ball of electricity that shocks enemies around for few seconds then explodes. The ball sticks to whatever it hits. (Priority: Very High, get it right after grenade launcher and gravity grenades)
  
• Secondary Upgrade: Shoots a projectile that expands into a dome that traps enemies and freezes them for few seconds. (Priority: Top, right after you unlock the gun)
  
• Passive Upgrade: Increases aoe of both modes. (Priority: medium, get it after you get more higher priority stuff)

Evaluation
Fantastic weapon, deals great damage, even if it isn't instant, the shock effect is useful by itself. The explosion will blast small enemies to bits, even medium enemies will go. Stasis effect is a must. It sets up for both primary fire of this gun and other (like RPG, grenades, charged plasma etc). Alt fire is a life saver, it is similar to blaster's emp but it can be shot at range. Making setups easier, and not requiring being close. The only downside is that some of your projectiles will also get slowed when inside of the dome. Not all though.

4) Railgun

• Primary Fire: Shoots a hitscan energy beam that hits enemies through walls. (Priority:Top, get it right after unlocking RPG)
  
• Secondary Upgrade: Small zoom that also lets you see enemies through walls. (Priority: medium-high, useful if you plan on shooting stuff through walls)
  
• Passive Upgrade: Shortens cooldown time, meaning increases rate of fire (Priority: medium, not necessary early or mid game, but it is very useful later when fighting airborne enemies, or enemies out of reach.)

Evaluation
A must have gun. Works great for everything. It is hitscan, instant damage gun that is good for picking stuff off, hitting stuff on the go and through cover and works mid combination of stuff when bursting down bigger things. It is also THE weapon to use for ALL boss fights. Secondary upgrade is useful but it isn't necessary. I get it usually mid game when enemies start to show up out of reach hiding behind cover is more useful. Passive upgrade is very useful, but only once you have situations where switching to other guns isn't applicable very much (like flying enemies, enemies at high ledges etc). It also helps with boss fights. Overall the first point for this gun is mandatory, get it right away after RPG, the rest is according to need.

5) Smartgun

• Primary Fire: shoots a slow moving homing projectile that goes through walls. Gun targets automatically and gives x-ray vision by default. (Priority: high, very useful not only for its damage and utility but also x-ray vision that gives you a heads up and a second or two to prepare)
  
• Seconday Upgrade: Charges up four strong projectiles that home and go through walls. (Priority: medium, get it mid to late game, useful for scarabs).
  
• Passive Upgrade: Increases damage of both fire modes. (Priority: very high, if you want to actually use this gun, this is a must)

Evaluation
A very useful weapon. Just unlocking it I advise to constantly have it on, unless you memorized enemy spawns. It will give you a heads up to what is coming, before they show up. The gun automatically aims, so as long as you aim in the right direction it will lock on and fire. Projectiles are fire and forget. They are slow, but they go through walls and home in directly on target. This gun is very useful against airborne enemies, and shooting things on the go without having to pinpoint aim (like railgun). Damage per projectile is not bad, and the consumption isn't as bad either. Secondary uses a lot of ammunition and takes a while to charge up, but deals massive damage and projectiles explode giving small aoe effect. In most fights this is too slow to use, but opening up this with big targets like scarabs it is great. It puts a big dent and once fired you can just move on.

Combat Gear

Unlike the guns, most of these upgrades are NOT as useful. There are few that help a good deal, but they are far and few. I will point them out. Mostly upgrading this should be last priority. There are about 2-3 points that are very useful and I would fit them inbetween some weapon upgrades. But only after you are comfortable with the guns you have. Meaning you don't feel you lack damage or utility.

Tactical Scanner

• Directional Sensor: Gives you indication where you are getting shot from. (Priority: start with it)
  
• Tactical Scanner: Gives indication where enemeis are at. (Priority: last, forget about this untill maxing yourself out)
  
• Awareness Module: gives indication where nano items are (Priority: last, forget about this as well untill the end)

Evaluation
Both upgrades are forgettable. The nano you can find guides for and little bit of searching around. Most stuff is not that hard to find. The enemy indicator is nearly pointless. Especially once you get the smartgun or you memorize where what is at.

Trauma Pack

• Hormone Dose: When health goes critical, time slows down and you speed up. (priority: medium-high, actually a life saver, fit it in when you can)
  
• Enhanced Hormone Dose: Increases damage resistance during perception mode (priority: low, pointless, since enemies are crawling slow)
  
• Double Hormone Dose: Increases duration of perception. (Priority: low, not necessary, again get later)

Evaluation
One point wonder. The other two upgrades aren't that worth it, but the first can be a life saver. What it is normally used for it, bee line to nearest health item, while enemies are slowing to a crawl. Fit this in eventually, the rest of the upgrades forget untill maxing out.

Hi-Capacitor

• Capacity Magazine:Increases ammunition capacity by 40. (Priority: high, fit this in, extra ammo can really come in handy).
  
• N.R.G. Filter: Pickups give more ammo and energy. (Priority: low, plenty of items around when needing to replenish, not necessary)
  
• Restore Compartment: Ammo and energy regenerate faster. (Priority: medium, can be useful, but mostly there are plenty of items around to replenish ammunition)

Evaluation
First point can be useful, especially once you start using RPG and Smartgun a lot. The second upgrade is worthless, the final is useful if you use one weapon alot. Like Railgun, or RPG or Smartgun. If you extensively hide behind cover and shoot rails or smartgun, then this will be helpful. I would still only put the first point, and then do the rest when everything more important is upgraded.

Medical Module

• Endurance Controller: Increases max health to 120. (Priority: medium, but only because of third upgrade).
  
• Enhanced Centrifuge: medkits give more health. (Priority: last, worthless)
  
• Nano Tourniquet: Increases damage resistance (Priority: medium-high, one of the few points that do something useful)

Evaluation
Overall this is worth investing into for the damage resistance point. Otherwise the 20 health increase doesn't do much. Eventually make your way to this, but get other things first.

Shield Emitter

• Shield Booster: Increases shield capacity up to 120. (Priority: medium, useful)
  
• Defensive Generator: increases rate of regeneration of your shield (Priority: medium, also useful)
  
• Regenerative Module: Shortens the delay for when shield starts regenerating (Priority: medium, good as well)

Evaluation
This entire section is good. Shield is a regenerating resource hence it is more useful in combat than health. Putting points into here when you can spare them is a good idea. All three are useful.

First get the Grenade Launcher and the gravity grenades. After that get the Electric Mortar and stasis grenade. After that I suggest getting shotgun, followed by blaster and emp. From here it is up to you. Those I believe are bare necesseties and after that it is just beefing up your damage output and reach.

RPG and Railgun should be grabbed as soon as they are available. Smartgun and Proximity Launcher are VERY useful but not as useful or necessary as RPG and Railgun. Get them after those.

Combat Gear updated should be an after thought, some like increased ammo capacity and trauma pack point are good to invest in between some upgrades that aren't absolutely necessary.

By the end of the game you will have enough nano to cover everything necessary and start putting points into lower required stuff. Key is having really useful upgrades as early as possible to have more options in fights.

Small Enemies

• In smaller quantities use shotgun, assault rifle (fully upgraded) or plasma gun (fully upgraded).
  
• Do not back yourself into a corner.
  
• Do not stick by explosive hazards.
  
• In large numbers shoot a gravity grenade followed by either regular grenade, proximity grenade or RPG. RPG has the biggest bang, but is overkill for small enemies. Proximity grenade is the most surefire way to kill since you control the blast.
  
• Do not get swarmed from multiple sides. If you see this happening, switch to Blaster and hit EMP, and then plow your way through with shotgun.
  
• On higher difficulties the suicide enemies pretty much instant death if not dealt with quick. Do not shy of using your CC shots on them, even if there are only couple.
  
• Small Scarabs can be a pain. Hit them hard with mines and rockets to get rid of them quickly. They will charge at you like gorillas.

Medium Enemies

• There are two kinds. The ones that shoot from a distance, and the ones that run at you. The latter have more health.
  
• Railgun will make short work of enemies that shoot at you from a distance.
  
• Try grouping them up with your CC shots and then open up with explosive weapon (grenade, proxy mine, RPG, charged plasma, electric mortar).
  
• Use railgun or smartgun on the move to thin them out a bit.
  
• Proximity Launcher airburst does wonders against these. It can catch multiple of them and does outstanding damage. Probably the easiest way to kill them in numbers.
  
• Fully upgraded Assault Rifle can make short work of them at close to mid range.
  
• Move in a way that makes them bunch up, line them up and then just blow them to bits.

Big Enemies

• Gorillas are easy once you know what they can do. They stomp at close range and charge at you otherwise. You can stop them in their charge with EMP from Blaster, EMP flachettes from Shotgun or stasis from Electric Mortar. Switch to RPG/railgun and other strong hitting guns to make short work of them. Finish them off (when you knock off parts) with Plasma gun or Machine gun (when upgraded. Key to fighting them is control and surrounding. Leave yourself room to strafe, and make sure they dont charge into explosive hazard that is next to you.
  
• If other enemies present that require immediate attention, use CC on them and then deal with the smaller more dangerous enemies first.
  
• Grenadier are similar to Gorillas, but they will fire missles at you from range. They also take more punishement. Same strategy but more movement is necessary or the missles will kill you. Switch between RPG, Grenade Launcher, Proximity Launcher, Railgun, Electric Mortar and Charged Plasma for maximum effect. Also use different CC when first one wears off.
  
• Scarabs are not a huge pain as they may seem. You can jump over their beam. Easy hit them with emp flachettes and, they don't move too much letting you get to cover if push comes to shove. They are usually accompanied by smaller enemeis which makes life harder. Open up the fight with Charged Smartgun and then CC smaller enemies and try to splash everything as best as you can.

Flying Enemies

• Railgun and Smartgun are weapons of choice. RPG is not bad either when you have alternate fire equipped. Use smartgun's scan to see how much HP they have. Use Railgun or Assault Rifle to finish off enemies with low health.
  
• General strategy is to move and shoot, smartgun works best of this. Railgun for finishing off is also superb. Run around shooting smargun several times then finish them off with railgun blasts.
  
• Standing in one place is a quick death, running close to explosive hazards is also a quick death. Pay attention to what is around.
  
• Worst case is using cover and shooting smargun/railgun through that cover.

Bosses

Boss 1

• Use pillars to avoid and minimize damage from his attacks.
  
• Use railgun to hit his weakspots.
  
• When he gets into his red stage, just shoot RPG, Railgun and Smartgun at center mass. No weakspots. Just unload your guns and fight ends.
  
• Enemies in between waves are fairly standard. Nothing too difficult.

Boss 2

• Boss itself is easy. Just shoot its legs off with railgun.
  
• Encounters in between can get rough. Kill the medium ranged enemies first. Locate them with Smartgun and then quickly kill them before dealing with bigger guys. Constantly move not to get hit by the laser and make sure not to run into a corner.
  
• Overall learning enemy spawns between phases is more important than fightig the boss. Boss by itself is easy and goes down with repeated railgun shots or guided RPG.

Boss 3

• There will be constantly spawning enemies, at ledges medium enemies that will shoot you, and small enemies will constantly spawn on the ground.
  
• Position yourself so the boss sucks in the barrel, they will be constantly falling from his activity, so no need to shoot them down.
  
• Use your CC shots liberaly. Small enemies will not stop coming. There is no need to always kill them, since the boss will do that as he sucks them in.
  
• Use railgun to thin out the enemies on the ledges. If they bunch up shoot a rocket.
  
• Shoot his weakspots after he sucks in a barrel, and that is that.

This should give enough information to know exactly what to get, how effective what upgrade is and general tactics against most situation. I may perhaps add a segment that tackles specific fights which can end up being difficult (like the bathroom brawl against hordes of small enemies), or the fight in the garbage grinder. But for now this should suffice.