Introduction
Welcome back, Commander
X-Com 2 was launched by Firaxis in February 2016 as the sequel to the new reboot of X-Com: Enemy Unknown and it's expansion Enemy Within. By now X-Com has become a mainstream name once more and brought back many previously thought lost gaming concepts such as permadeath being the norm and actually being able to lose at the game. Its squad oriented combat system, the detail and necessity to manage, equip, and properly skill your troops in order to succeed came as a breath of innovation among the gaming world where the turn base strategy had seemingly all but died out. Jake Solomon and the rest of the crew at Firaxis have done a wonderful job of bringing a classic back to life and back to modern gaming. After the success of the first game they took a lot of fans reactions seriously and worked with the public response to help shape the sequel and that becomes very evident in X-Com 2. Things the fanbase desired most or were added in by steam mods were adapted by Jake and his team to be features programmed into the second game. The game is sleek, shiny, well polished and clearly a labor of love.
In the wake of ADVENT, things have changed
Much of what we knew and loved about the first game remains. However the parts that fans and even Firaxis might not have been 100% satisfied with have changed. While the core concept of the soldier squad based combat remains largely the same as the first game the strategic level has changed dramatically. The player no longer sits looking at the holo-globe waiting for alien activity to happen and then responding. Many fans pointed this out as too passive to be satisfying, and Jake Solomon agreed. During interviews and broadcasts Jake spent some time talking about he wanted a more engaging strategic layer to the game. He talked about spending days with Sid Meier where each of them designed a strategic layer, made a proof of concept model and played each others concept to critique and improve upon what they came up with. The result in X-Com 2 is a totally new system where the player moves X-Com's mobile base around the world map to preform missions, gather resources, access the black market, and even evade UFO's trying to intercept the base.
In early press conferences Jake Solomon stressed that he wanted to pressure the players more than in the first game. As you may have seen in my LP of the first game it was almost never advantageous to advance rapidly during a map. Many turns would be passed moving half speed and overwatching. This lead to a slow and somewhat stale experience and Jake sought to change this. Most missions are now under time limits, some easy, some very strict. This met with a lot of mixed response from fans at launch, but like it or not Jake succeed in his goal of putting pressure on the players. It's now very rare to be given much more than a turn of breathing time until you need to be doing something important. For the most part I think after the initial shock wore off that this was a very good change. While the days spent half moving and overwatching were the safe, smart play, I don't feel they were the most exciting or interesting. The only minor criticism I have about this new mechanic is that it sometimes runs into problems with the alien pod activation mechanic. Jake wants you to be advancing in combat, to move and out flank your enemy, out play them to get the advantage and that is fine, the game does that well. When you have to advance and move because of a time limit you run the old risk of advancing up on a first group of aliens and triggering a second group, thus ruining your day. The two mechanics sometimes collide at odds with each other; one rewards you for aggressive advancement, and the other punishes you for it. It's not a perfect system, but I would consider it a large improvement overall.
The Resistance is... Disorganized...
The story takes a huge turn from the narrative we knew and may have expected. In Firaxis' first X-Com the story follows the theme of the original by Julian Gollop; A multi national organization is founded to investigate and respond to alien activity on a global scale while doing the best they can to keep the public from finding out and setting off global panic. The aliens have come to earth for nefarious reasons, biological testing, DNA splicing, and infiltrating our governments to quietly and secretly take over. Now in X-Com 2 the story is different. The aliens have already won that war. For twenty years they have controlled the governments, they have built huge utopian city centers to win the populace into accepting a puppet government called ADVENT and broadcast their propaganda 24 hours a day through all forms of media, and perhaps most effectively by providing free medical and aid care to those that become ADVENT citizens. Major ADVENT centers have opened 'gene therapy' centers and have wiped out disease and hunger in the sprawling city centers. luring many to accept the ADVENT rule in exchange for free medicine, food, shelter, and security.
Outside of the ADVENT city centers lives the fringes of society. Those that know the aliens are tyrants and not to be trusted. The resistance lives, but the scattered remnants of freedom fighters lack the power to strike back at the ADVENT government with any meaningful force. This is where the player enters the game. Given a small handful of soldiers, a stolen alien cargo barge, a former ADVENT scientist, and an engineering prodigy, the player must rally the resistance cells, strike back against the occupation, and uncover the mysteries of the alien occupation. Why did they come here? What do they want with humanity? What happened to the leaders of the aliens, the Ethereals whom haven't been seen since the war was concluded?
The challenge set before you will not be easy
For those of you who watched my first LP you know what to expect to see here. For those of you that are new or did not watch my previous LP, let me explain. I will be joined by my good friend and all around Canadian buddy, Guava Moment while I play on the Commander difficulty and we discuss our strategies and tactics through out the game. My previous LP's goal was to be a strategy guide for players that were having difficulty going from the normal difficulty level to the Commander difficulty. That will be my primary aim here as well. I will be dissecting my strategy, explaining why I do what I do, how to manage resources, troops, the world map, everything I can think of that will help fellow players out. I certainly encourage questions in the thread too. If you have a question about something, ask away and I'll do my best to answer, in thread or in video.
X-Com 2 opened the doors up the Steam Workshop and there are a metric fuck ton of mods available to the game. When I play for myself or my stream I often run a lot of them. There are many mods that are wonderful and do very cool an interesting things from gear, weapons, mechanic changes and even entirely new soldier classes. That said I will be running with a bare minimum of mods for this game. My aim is to give as pure a strategy guide as I can so I will not be using mods that change the game in significant ways. Most of what I will be using will be cosmetic mods for soldier customization and UI things. Of particular note is the flank preview mod, which changes a part of the UI to tell when a soldier would be flanking a target from the highlighted position, and the True Retroactive AWC mod. The AWC will get discussed in the LP when it gets built and I'll explain the significance of this mod then. Suffice to say though, I feel the mod implements the AWC feature the way it should have been implemented by Firaxis to begin with. Guava is being insistent on some other mods, like the evac all button because he is a big impatient gorilla, and some other mods that are just for fun.
There have been two content DLC's since the launch of the game, Alien Hunters and Shen's Last Gift. I will be playing with both of these enabled. They add a few new story missions to the game and reward the player with lasting upgrades for their squad of soldiers. Alien Hunters in particular is... questionable about some of what it added. However it's still a cool new thing that I will be showing off and it's negatives are relatively short term compared to its benefits.
Some secrets are better left untouched
This is the no plot spoiler policy! The game has a lot of new elements and an interesting story line. I really like how they told a story from the losing end of the war and dealing with the whitewashed dystopia the ADVENT have created. Please no spoilers about plot themes, missions or anything of that nature. This goes for the DLC too since it's newer and have their own mini-plots to tell. That said, fair game on most everything else since things that are not story related are very similar to the first game. Feel free to talk about weapons, skill choices, aliens that are not the new DLC ones, and things like that.
Table of Contents
Operation Gatecrasher Full Post
Operation Nigel Cummings' Fart Full Post
Operation Zen's Testicles Full Post
Operation Zen's Wail Full Post
Operation Sleeping Throne Room Full Post
Operation Dread Wail Full Post
Operation Meat Root Beer Full Post
Operation Hard Gay's Secrets Full Post
Operation Lost Tower Part 1 Full Post
Operation Lost Tower Part 2 Full Post
Operation Lost Tower Part 3 Full Post
Operation Agrippa's Something oughta go here Full Post
Operation Wei Shen's Cummings Full Post
Operation True Roman Testicle Full Post
Operation Regal Beast Full Post
Operation Bad Wrong Chicken Full Post
Operation Oh My God, Valley Full Post
Operation Secret Rage Full Post
Operation Naked Serpent Full Post
Operation Rock Rage Full Post
Operation Naked Prince Full Post
Operation Hard Gay's Dick Full Post
Operation Bad Wrong 'ard Full Post
Operation True Roman Fire Full Post
Operation War of the Llancarfan Full Post
Operation Lune's a top agent and an even better shot Full Post
Operation Unfortunate Granola Full Post
Operation Saga Full Post
Operation Syphon Filter Full Post
Operation Jagged Hot Center Full Post
Operation Miserable Tomb Full Post
Operation Balls World War Full Post
Operation Shambling Fire Full Post
Operation Flying Fire Full Post
Operation Club Face Full Post
Operation [REDACTED] Pants Wrestling Full Post
Operation Oh my god, Shield Full Post
Operation Dismal Granola Full Post
Operation Jack Pronunciation Full Post
Operation Plot Exposition Full Post
Operation Meat Touch Full Post
Operation Leviathan Full Post
Extras
The big sign up pool can be found here - http://www.mediafire.com/download/8...t+Goon+Pool.bin
There are several names with asterisks by them, these are the people that requested resistance style armor that I was unable to preset them into since that requires re-equiping them with a different armor, something you cant do in the creation pool.
The art of X-Com
While it's easy to look at the graphics of X-Com and see how nice they are, the actual art behind the game is equally, if not more, impressive. There are many little touches the game has that I really appreciate and look at wanting more. As an example of something that won't be shown much in the LP if at all are the loading screens. These screen contain beautiful images. Images which are ADVENT propaganda posters, featuring imagery such as rows of the ADVENT troopers behind bright colors and the ADVENT symbol. Another is two regular humans side by side, flanked on either side by ADVENT troopers. The man and woman are smiling and the troopers look steadfast and diligent. The message there is so clear even with out words, 'ADVENT is here to protect the people. We make you safe and secure so you can lead happy lives'. I feel like it's a bit of a shame I can't play a game more immersed in this oppressive propaganda ADVENT controlled world. Something to the theme of Mirror's Edge, just to run through it, see it all and try to aid the resistance somehow. Or a Shadowrun styled game in an ADVENT city center. An underground cell working in the shadows of the clean pristine ADVENT city center. So much potential. Please check out the official X-Com2 art blog here.
The artists of the game even do really subtle things with their art. Going back to the loading screens, they made many many different images of ADVENT propaganda, but they also made several X-Com propaganda images as well. On top of that a sneaky thing I never realized until I read the art blog was that which loading screen you see is based on how far into the game you are. The loading screens in the early game will feature all ADVENT images, but as you progress farther into the game the more common a loading screen will be of X-Com propaganda. It's another nice touch and something I'd love to see expanded on in some way. At most in game you'll hear Bradford talk about the resistance trying to gain a following and mention how it's tough when ADVENT propaganda is whispering in your ear 24 hours a day.
Lastly I'd like to mention the art design of the cities. X-Com really nails what I refer to as a 'White Dystopia'. It's a Dystopian future, where everything sucks, the average man is in a bad place, but everyone accepts the situation willingly. Or at least most of everyone. It's a Dystopia that masquerades as a Utopia. Everyone in the city centers are happy, but if you start examining their life, what they had to give up, and most importantly the central power that makes that way of life and rules everything around them, you start to realize the horror of the world they live in. I feel the game sold this concept really well. It's very easily and plausible to imagine and understand the allure of ADVENT city centers after the wake of a global war and you can't really blame the population for wanting a life that isn't spent on the run, or sick, or hungry. People value stability in their lives nearly above all else, so it isn't such a far fetched idea to see how things got to where they are in the X-Com2 future.
Concealment and Ambushes
The majority of maps in X-Com2 start your squad in a concealed state. This means the aliens are not aware of your soldiers and you will actually have to get their attention before combat begins as normal. This allows a player to potentially scout the map out or find a group of alien soldiers and prepare an ambush to wipe them out with a minimal fight. Soldiers will remain concealed unless a few things happen; They are spotted by an enemy unit or a civilian, you create a loud noise such as kicking open a door or smashing a window, or you open fire. The particulars of what to do during your concealed time differ between maps based on terrain, objective, and time limit. Predominantly though I will use my concealment time to find the first alien pod I can and ambush it as quickly as possible, and preferably before I find a second alien pod. Limiting your firefights to a single alien pod at a time is always the best option.
On the subject of ambushes it's important to know what you're doing and to set up properly. The first shots you take coming out of concealment matter a lot. Overwatch shots don't take the usual penalties associated with overwatch and the first shot is almost always going to be against a target out in the open with a much larger chance to cause a critical hit. Larger pods of aliens will often times bunch up nicely for you and allow an easy opportunity for your opening attack to be a grenade that hits three targets at once. It is also important to plan around the possibility that your initial ambush doesn't kill everything. This can happen because of missed shots or simply too many enemies to drop in a single salvo. While putting the entire team on overwatch and creating a giant death trap of an ambush is generally a good idea there are occasionally things to watch out for. If you do put everyone on overwatch then that means if any aliens survive they will scatter to cover and then have their full turn to act before you can react. This can potentially mean an alien that escapes the ambush can move to cover on the scatter, then move forward to flank a soldier who was close to the ambush point. I would advise some distance between your soldiers and the ambush point if you are going to go all out on the overwatch trap. Otherwise consider selecting someone to not overwatch, just in case. I prefer Rangers for this mostly because of Slash. If the ambush fails and an alien escapes into high cover Rangers have a good set of skills to rush them and cut them down.
Enemy Mechanics
Enemies retreat! If you kill all but a single alien sometimes that enemy will flee, running off into the shroud to find another alien pod to attach itself too. Thankfully this doesn't immediately activate the new pod, it only groups the survivor with them, so you will have to activate the new expanded pod separately. I'm not going to say for certain, but anecdotal observation would suggest a pod that receives a fleeing member will begin to patrol more aggressively in your direction. It is usually a mixed blessing to have an enemy retreat from combat like this, typically if they stood and fought one lone alien wouldn't be able to do much and would be gunned down the following turn and now it is instead adding its strength to a new encounter you will have to face at full force plus the extra alien. Sometimes this can buy you time in a close fire fight and give you a turn or two to reload and apply medkits. It comes down to the individual situation most of the time and how you can best spend the momentary respite.
Sectoids
Sectoids! Let's talk about what was the weakest enemy in the previous game. Twenty years of screwing around with their DNA and mixing in human DNA has lead to a larger more humanoid alien. The redesign is pretty powerful, sectoids are no longer mouthless skittering grey aliens that gave the feeling of an alien insect more than a person. Now they talk upright, have more facial features, viscous looking teeth, and are just all around much larger than before. Nearly twice as tall I'd say, though I'd need good art or comparative pictures to be sure. They are designed to look much more threatening now rather than 'tiny little gray that will probe you'. They're here as alien backbone to the ADVENT troopers. Well, if they really accomplish that feeling to the game player is debatable, but the art design of them really turns up the threat level of them.
Sectoids can and can not be dangerous, it's situational and that is where I believe the difference in opinions between myself and Guava lie. Let's look at the three things you are likely to see a sectoid do. First off they have a Psi Reanimate, which a new twist on things. They will resurrect any fallen human/ADVENT soldier as a zombie. The zombies aren't very threatening, but they will shuffle around and punch your troops. I assume. I have yet to actually see a Psi Zombie accomplish anything. The AI will usually prioritize this action over the sectoids other two options as long as there is a viable body laying around for it to reanimate. Psi Reanimate is what Guava refers to as 'The Dumb Thing' that sectoids can do, and with fair reasoning. The zombies themselves are pretty weak and likely to go down in 1 hit with a crit because they don't take cover and don't have the natural crit mitigation bonuses that normal melee units have. Creating a Psi Zombie can be thought of the sectoid doing nothing on its turn as long as you kill the sectoid on the next turn because when the sectoid dies so does the zombie, sort of like mind merge in the first game. The second thing a sectoid can do is attempt to psionicly attack a soldier. Their ability is called Mind Spin and it can inflict various degrees of bad effects on you soldiers from disorienting them, to stunning them, to outright mind control. This is the ability I feel is the most threatening, though Guava disagrees. Mind control is super bad, and even more brutal early on in the game where breaking the control will be harder than later on. Lastly sectoids have a plasma pistol much as they did in the first game. The big catch here is that they have significantly higher aim than they previously had and are a credible threat to actually shooting your men. This is what Guava feels is their most dangerous action and it is possible for a full damage sectoid plasma shot to kill a 4HP rookie.
Back to why I said they are dangerous situationaly; Alone they are not much to fear. A squad of 4 rookies can handle a lone sectoid pretty much no matter what. I feel that sectoids become more dangerous when they have other enemies around to screen them or stack the numbers a little. As I said by themselves no one is going to worry over a psi zombie or a mind spin. Get in a fire fight that is 5v5 or something like that and they can be a bigger problem. You may have to spend significant effort to kill a sectoid hiding in the back in full cover to kill it and a psi zombie while having less actions left over to deal with the rest of a situation. Perhaps it can't be said sectoids are dangerous in their own right, but they are a definite support hazard to watch out for. With a mind spin your 5v5 fire fight may be looking like 5v4 for the next turn, or 6v4 and then you're in a lot more danger than you were just a moment ago. It's situational and can depend on how easily and safely you can dedication a number of actions to dealing with a sectoid once it's start up its psi powers.
Weapon Modifications
X-Com2 introduces a robust weapon modification system that allows you to add parts to soldiers guns to give them extra abilities. The parts are salvaged from fallen ADVENT and aliens, or purchased from the black market, and equipped in the armory to bolster your soldiers weapons. There are six kinds of mods, ballistic weapons may equip one mod per gun while advanced guns may use two mods per gun, with a continent bonus that will increase the mod limit by one further. By default weapon mods are a one use item, once you attach them to a gun they can be replaced, but not reused. If you replace a mod with a different mod the old one is lost. This can be changed by a continent bonus. Having both of these continent bonuses can lead to some seriously powered up guns for your team to use. Each individual type of mod also comes in normal, advanced, and superior quality levels.
So what do the mods actually do? Well let me list the seven kinds and my preferred use for them;
Stocks allow missed shots to deal guaranteed damage. From 1, 2, or 3 points dependent on the quality of the stock. Guaranteed damage can not be overvalued. Being 100% sure to deal 2 or 3 damage can make a world of difference when finishing off wounded aliens. Personally I love these things on rifles. Rifles are the only weapon given to specialists, whose skills revolve around their gremlin drone and utility functions, they never really gain the ability to do great deals of damage with their rifles.
Scopes increase accuracy, exactly as you may expect. 5%, 10%, or 15% based on scope quality. In theory everyone could use a scope but are usually in much shorter supply than needed to be able to put a scope on every gun. Typically I will put these on sniper rifles first with surpluses going to grenadiers to shore up their lower aim scores, or any soldier in particular that I feel needs a boost. Every soldier can benefit from a scope, but the short supply means picking who will get the few scopes you do come across and make the most of them.
Repeaters are a barrel modification that give the weapon a small chance to instantly kill any target they hit, in game it's termed as an execution. At 5%, 10%, and 15% the odds of an execution ever going off are fairly slim. In my personal preference I prefer things that give me reliable results such as stocks working 100% of the time even if the effect of a stock isn't nearly as impressive as a repeater when it works. A single low grade repeater in a squad isn't going to do much, and would only be noticeable once every 20 shots, statistically. However, you throw 3 of the superior repeaters into a squad and suddenly the odds of seeing an execution jumps up near the point where you might expect an execution on every other turn if the whole squad is firing. I feel like repeaters are a tactic that needs to be used in mass in order to push up the chances of seeing them in action, where as a lone repeater may never make its presence felt. That all said, I will typically put repeaters on shotguns and rifles. Rangers are often times tasked to put up big damage against tough aliens and a repeater can certainly do that if they trigger. Repeaters on rifles are often times from a lack of having anything better out there, but it is worth noting the combination of a stock and a repeater; guaranteed damage every shot with a small percent chance to instantly kill the target, every shot.
Laser sights grant extra critical hit chance to weapons, starting at 40% at point blank range and diminishing as the distance to target increases. This is a fairly obvious choice for shotguns as they are meant to be used at very close ranges, and often from a flanking position to give a ranger a very, very high critical hit chance. While I haven't personally put them on other classes very often I can see some draw to it. I feel they're sort of like scopes but less powerful on non-shotguns, every gun could benefit from them but you're more likely to have better options and not likely to have a surplus of laser sights laying around.
Extended Magazines do what they say on the tin, they increase a weapons magazine size by 1, 2, or 3 shots depending on the quality of the mod. The obvious candidates for these mods are the grenadiers machine guns, whom may burn through ammo rapidly do to skills such as Suppression, Chain Shot, or Hail of Bullets, all of which require additional ammo to be spent. On top of machine guns only having three shots per reload unlike rifles and shotguns with 4 per reload. Surprisingly sniper rifles also really benefit from extended magazines. In part because firing the sniper rifle is a full turn action thus preventing a turn spent reloading as a first action and firing as a second action, as can be done with all the other weapons. So having more rounds per reload allows combat to go on longer before a sniper needs to spend a turn reloading instead of shooting. The other big use I find of extended magazines on sniper rifles comes with the skill Killzone, allowing a sniper to take as many overwatch shots as they can during one turn, one shot per target. Naturally having more rounds loaded means more potential shots being fired by this kill.
Auto Loaders allow a soldier to reload a weapon 1, 2, or 3 times in a mission with out spending an action to do so. These are always the first reloads of the map so unfortunately you can't skip using your free reload in an attempt to save it for later on in a more critical situation. Still this mod can be super handy and my auto-loaders will typically be found on my grenadiers to help make up for their below average ammo capacity.
Hair Triggers give a 5%, 10%, 15% chance to not use up an action when firing the weapon. Like repeaters this can be a huge deal, when it happens. The odds are pretty low that the effect will happen but when it does it can mean getting a second shot against a dangerous alien, moving out of harms way, or otherwise avoiding a hard time. Or it can happen when the situation is well in hand and the last alien just died. It's a big gamble on when and in what situation the effect will trigger. Typically I place hair triggers on shotguns for double shot rangers or hit and run tactics. My feelings on these are pretty similar to repeaters, they can occasionally be super useful but have too infrequent a chance of working to be relied on.
Retaliation Missions
Retaliation missions are the new Terror missions. They play out almost the same with the same sort of mechanics to worry about. Namely rescuing civilians before they are all murdered by the aliens. There is no hard turn timer like most other missions but a good rule of thumb to keep in mind is that the aliens will kill one civilian as long as there is a alien pod untriggered and roaming around in the shroud. This generally means you have to be quick with things. You can optionally choose to seek out the aliens and deal with them before they can kill all the civilians or you can move out and rescue the civilians yourself and deny the aliens the ability to kill enough of them to cause a mission failure. Retaliation missions can play out very differently from each other solely based on where the civilians are and map lay out. Sometimes you may be able to rescue 6 civilians in short order at the start of the map which will give you a lot of breathing room to take things slower and safer. Sometimes you may barely find any and need to rush forward to either find civilians or find the aliens and stop them first.
A big new wrinkle to the retaliation missions is the new alien unit Faceless. Faceless are huge jerks that are disguised as civilians and will transform when you get too close. On their own they aren't so bad, they only melee attack and for rather low damage. The big problems that come with faceless is when they transform and swipe at you while you are busy dealing with other aliens. Notably their swipe will destroy cover in a small area of effect potentially leaving a wounded soldier exposed and vulnerable for other aliens to pick off. Faceless are the most difficult to deal with early on in the game when soldiers have low health and ballistic weapons may take several shots to drop the 10hp monsters. Once the first armor and weapon upgrades are equipped they become pretty tame. There are ways to detect faceless ahead of time as well, battle scanners and the specialist ability Scanning Protocol will reveal faceless. Lastly any faceless left disguised once all other aliens are killed will drop their disguise and rush at you. This isn't really threatening at the end of the map and is more of a convenience thing rather then having to hunt them down and check every civilian left on the map. So good thinking there Jake.
Guerrilla Missions & Dark Events
Guerrilla Missions are the new take on abduction missions for the second game. Where before abduction missions meant managing panic across the locations they were happening in Guerrilla Missions allow Dark Events to be countered, as well as offering a supply or personnel reward for the mission. Talking about guerrilla missions really means talking about the dark events because they are so interconnected. Every month ADVENT pushes forward these dark events that benefit their side of things. These effects can vary from denying XCom supplies, making XCom spend extra resources to accomplish things on the geoscape, giving ADVENT troops additional armor, placing Faceless into missions there otherwise wouldn't normally be Faceless, or outright advancing the Avatar Project progress bar. There are a lot of dark events and choosing which one you want to prevent from happening is going to play the larger part in deciding which guerrilla mission you choose to take. As a general rule I would always recommend preventing the Avatar Project advancements. Besides those events it becomes hard to write a strict rule of priorities, there are a lot of events and the kind of situation you are in when they come up can vary greatly. Taking your time to consider and weigh the significance of each event is the key here, but there are at least a few events I can mention as low priorities. Vigilance increases the alien spotting range during the concealment phase, and while that might be a pain in the ass, it's a very small and niche pain in the ass. ADVENT Midnight Raids increases the cost of recruits by 100%, again potentially being a pain in the ass but unless you are hurting for manpower it shouldn't be a factor. Dark events also take a while to go into effect after you have to pick which one to disrupt so if midnight raids are going to be a problem you may be able to get around it by hiring rookies right away, before the event triggers.
The guerrilla mission and dark event system is a lot more in depth and varied than the abduction missions of the first game. It's not hard to see the similarities in them, you're given three options and can only respond to one of them, but the added element of the dark events add a layer of complexity over that of the homogeneous abduction mechanics and panic board of the first game. Guerrilla missions are also now rewards, or counters, to changes in gameplay rather than being than being the direct thing that will make you lose the game like in Enemy Within, ie. the thing that panics counties until they pull out and you lose. In the first game abductions lead to panic, panic leads to countries pulling out, which leads to game over. In XCom2 the Avatar project ticks along a timeline and can be influenced by the guerrilla missions, but isn't determined by them. It's a good design change and improvement over the first game.
Guerilla Training School
Let's talk about the Guerrilla Training School, or the GTS. It's version 2.0 of the Officer Training School from the first game and has all of the original functionality you may know and expect if you played the first game. This is where we go to spend supplies on battlescape benefits such as unlocking large squad sizes, gaining a bonus to the concealment phase, getting extra loot from the ADVENT drops, increased exp per kill, and so on. There are a lot of beneficial abilities to purchase in the GTS and you want them all. That said, you are not likely to be able to afford them all. Supplies are always in short supply so I would consider it a pretty big luxury to be able to purchase everything out of the GTS. The obvious first picks are the squad size upgrades. Perhaps none obvious is Vulture, the upgrade that increases the amount of loot gained from ADVENT drops. It's a long term investment that pays more the sooner you buy it and all the extra weapon mods and PCS's you will gain from it will easily pay back the purchase cost of Vulture. Integrated Warfare boosts the bonuses of the PCS's you plug into your soldiers skulls and may be nice if you have a lot of PCS's, but is very optional in my opinion. There are also skills that will affect an entire class, one for each soldier class. These offer a bonus specific to the class type and can vary in power. Purchase of them would be largely based on the player and play style. My opinion being the Ranger and Specialist upgrades being the strongest but that is because they benefit my preferred playstyle the most.
A great new feature to the GTS is the ability to train rookies into a desired soldier class. One soldier at a time may be trained from a rookie into a soldier class type of your choosing over the course of 5 days. This is a huge quality of life addition to the game and praise be unto Jake for fixing his game in this respect. This solves a common problem of having a lack of a particular soldier type and having to rely solely on random rookie promotions, such was the case in the first game. A secondary benefit is also just being able to avoid having to deal with complete rookies that have zero skills and are largely useless. With the GTS you can at least give a soldier one promotion before they have to face the aliens, giving them a little stat boost and the starter class skill. Overall this is a wonderful addition to the GTS and makes managing your soldiers much easier and less stressful.
New Armor Mechanics
Armor is a new mechanic in XCom 2. "But wait...?" I hear you saying, armor was always a thing, even in the first game. Well sort of. Armor as equipment isn't anything new, but previously all armor did was add to a soldiers HP. New to XCom 2 is the armor mechanic. Now armor refers to a damage mitigation provided to the wearer. For a quick example, let's say a soldier with 2 points of armor is shot by a 6 damage laser. The soldiers armor will mitigate 2 points of damage and the soldier will receive only 4 damage. This effect will apply to every shot the soldier takes, and doesn't go away after the first hit. Very simple mechanic and very easy to see just how valuable armor can be in this game. Armor can prevent a significant amount of damage to your troops. Or the enemy, as they will have armor too as the game progresses.
So how do you deal with armor? That is where the 'shred' mechanic comes in. Certain attacks, most commonly explosives, will destroy the armor points of whatever they hit. Let's say we throw a regular grenade at an alien with 2 armor points. The grenade will deal 1 point of 'shred' which destroys one point of armor, 1 damage will be blocked by the second point of armor, and 1 or two points of damage will be dealt to the alien. From then on the alien will only have 1 point of armor left. Shredding still requires you to deal with the enemy armor, but only once instead of leaving it there to mitigate damage on every successive shot. It's a very good idea to prioritize your attack order when dealing with armored foes. Start with the attacks that will shred first and then follow up with regular attacks to deal the most damage.
ADVENT Mechs
Mech's are back! Only this time they aren't on our side. ADVENT has produced mechs very similar to what was in the first game, only they are wholly robotic with no organic pilot. They have a sizeable chuck of HP and usually the first things to be seen with armor points, making them take some significant effort to bring down quickly. Despite their toughness they are not incredibly dangerous. Their main gun is only a little stronger than the standard ADVENT troopers gun. What can be dangerous about them is that the do not use cover and can happily charge right at your lines to get around your cover and shoot you in the flank. Additionally they carry a micro-missile pack on their backs which functions like a grenade launcher, dealing small area of effect damage to a radius and destroying cover. On it's own not too dangerous, but can easily lead to a soldier taking a little damage, losing their cover, and being exposed to a out of cover critical hit shot from another enemy. Guava claims their missile use is super rare while I maintain that firing missiles is usually their number one action of choice, so your results may vary.