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Know Your Enemy: XCOM Enemy Unknown Strategy Guide

XCOM: Enemy Unknown

Know Your Enemy: XCOM Enemy Unknown Strategy Guide

XCOM: Enemy Unknown was a surprise hit for me. After reading lots of glowing reviews last fall I took a chance with it and never looked back. Nearly 100hrs later I still haven't tired of the awesome tactical gameplay, and it's one of the few games single player games that I've played enough to improve my game immensely. It's a good thing to as the higher difficulties are absolutely brutal and unforgiving, and Ironman mode strips away your ability to reload when things get well and truly bad. After my first successful Classic Ironman playthrough I've decided to put down my own thoughts and feedback on how I was able to survive the alien invasion. I've broken it up into four parts: Base Management, Squad Management, and Combat Tactics; each area is vital to success, with base management easily being the most un-intuitive.

Note that I played the Xbox 360 version.

This guide assumes that this is not your first time with XCOM. Only venture into Classic once you've mastered Normal, and only venture into Ironman mode if you're willing to start over if things go horribly wrong. Also it should go without saying, but definitely turn off the tutorial. It helps explain some aspects of the game but really screws up your early game.


Base Management

Starting Country

When you first begin the game you get a choice of five starting locations:

  • Africa - 30% bonus to monthly earnings
  • Asia - Halves the cost of Foundry and OTS upgrades
  • Europe - Halves construction and maintenance cost of Labs and Workshops
  • North America - Reduces all aircraft costs and maintenance by 50%
  • South America - Autopsies and Interrogations happen instantly

Africa is just too sweet not to pass up. Sure the bonus isn't that big in the very early game, but by taking Africa you can lose the other two countries within the continent and still get the bonus. If you don't take Africa, I'd recommend North America and go after satellite coverage for Africa immediately. North America's bonus isn't all that useful until you need Firestorms in the late game, but USA alone gives a huge chunk of money that's useful in the beginning.

Remember, on Classic mode you WILL lose some countries to panic, so it's important to know which bonuses are crucial and which countries you can lose. Africa and North America are critical, South America is completely worthless but it's only two countries. Out of Europe and Asia I would always try and get Europe's bonus. Not only are the countries generally better payouts but reducing the cost of Workshops will help immensely in the long run. You don't need to build Laboratories at all, and I'll get into that later. If you manage to get Asia's bonus as well, good on you, but by the time you've got it covered you've probably already got plenty of money to use on the Officer Training School upgrades and Foundry. For some reason I end up losing Australia in every game I've played...

The Layout

After your initial mission (which you should be 100% perfect on, otherwise just start over now), check your base layout. You need at least one steam vent that's not on the bottom row. If you have two near each other, great, but only one is really necessary. If it's too close to your initial uplink, i.e. within the 2x2 grid you're going to build of satellite buildings, just start over.

It's incredibly important that you build your base correctly, and the game doesn't emphasize this enough. The adjacency bonus you get for many building types is crucial; specifically your Satellite, Power, and Workshop buildings should all be adjacent to each other. Since you start off with only a Satellite Uplink to the left of your initial access lift, this means creating a 2x2 block right there. To your right you can eventually build some one-off buildings like the OTS, Foundry etc. On the second level you'll want a 3x3 grid of workshops. Yes, 9 workshops in total. Why? Well they reduce the cost of damn near everything, they give you more engineers which you need for additional uplinks, and their adjacency bonuses gives you money back from building stuff. On the third level you'll want to start your power generators, ideally beginning with a thermo generator over the steam vent. Eventually you'll have a 2x2 grid of Thermo, Elerium, and Power Generators. However, you'll need more power just to tunnel that far down so you will need to build a power generator or two at the top. They can be removed later for late game buildings like Psi Chamber and Gallop Chamber.

As you can see, you never need build Laboratories, which is an odd bit of imbalance in the game. Labs and scientists will reduce research time, which seems great but you need money to build anything you research anyway, so it's pointless to research faster when you can't afford to build the new items. This is where getting Europe's bonus comes in handy, as the Expert Knowledge bonus really renders any Labs obsolete.

The Fist Months

How the first four months of the game go will ultimately determine whether or not your brave men and women of XCOM come away as heroes, or coffins.

First, ignore the storyline and the terribly annoying Dr. Vahlen. Don't even worry about building an arc thrower or Containment Lab for the first few months, you've got enough to worry about. Only after you've got a decent economy going and some promotions should you even think about capturing aliens alive.  I waited all the way until I had full satellite coverage on each country that hadn't pulled out before I ever captured an Outsider.

Your priority every month should be to build a Satellite Uplink and 2-6 satellites depending on which month it is.

  • Month 1 - Build and Place satellite, preferably USA for the biggest cash boost.
  • Month 2 - Build Satellite Uplink and 3 Satellites. Get Africa covered if you didn't start there. Build Power Generator, Access Lift, start a workshop or two, maybe OTS.
  • Month 3 - Build Satellite Uplink and 3 satellites. Work on getting continent bonuses, and manage panic levels as best you can. It's ok to lose 1-3 countries. Should have OTS by now. Get a thermo generator. Make sure you'll have enough engineers and power to build a Nexus next month.
  • Month 4 - Build Satellite Nexus and as many satellites as you need to get full coverage. This will essentially lock down panic levels for the rest of the game, and also prevent any further abduction missions.
  • Month 5 - Money Money Money! Enjoy getting about 1500 a month, go a little crazy on OTS upgrades and some Foundry projects, but make sure to keep building workshops as well. Remember to always save some money to buy any new toys you research.

Note that you can purchase satellites even while the Uplink is still building. This is a critical piece of information that the game does not telegraph. It warns you that you cannot launch them, but you can still build them and have them ready to go once the Uplink is finished. Be very aware that Uplinks take 20 days to build, and satellites take 14. Excavating takes five. Timing is everything!

Always wait until a few days before the end of month Council Report to launch any satellites. Especially in Months Three and Four when you're going to be worried about Panic Levels, you could always get a mission that could reduce the panic level. Since launching a satellite automatically reduces a countries panic level by two, you can use satellites to save a country before the end of the month, but only if you don't get a mission there first.

Technically if you lose less than two countries, it would be better to build 2 Nexus, but you would have to be really lucky with panic levels, and frankly you're probably screwing yourself on getting continent bonuses. With three Uplinks and one Nexus you can cover up to 14 countries, which should be plenty. In my most recent Ironman run I lost three countries so just the one Nexus worked out fine.

The difficult part of the initial few months is that you'll be spending about 80% of your cash on satellites, uplinks, and the necessary preqs for them (workshops for engineers, generators for power). Do not waste what little money you have on expensive upgrades. Getting on OTS in month two or three is fine, as the Squad Size upgrades are obviously huge and incredibly cheap.

If you follow this schedule, you should reach Month five with about $1500 in monthly income and you can really start digging into Foundry Projects and OTS upgrades. Many Foundry projects are superfluous but taking a SHIV along once you reach a six man crew can be quite useful.

In terms of items, always go after armor first and weapons second. Research alien materials in the beginning and get carapace armor for everyone when you can. Remember that the vests take up a backpack slot and many times in the beginning having a grenade is the difference between life and death as they can one-shot the little grey Sectoids.

Remember to only buy what you need for any one mission. Although the game makes it kind of a pain, you can and should strip down any soldiers you're not taking on a mission (the game does do this automatically for any injured troops). In the beginning every dollar counts, so never buy more than what you need for a single mission; it's pointless for someone to wear carapace armor if they're sitting in the barracks.

Make sure you keep up with building interceptors along with your satellites. One interceptor per continent is really all you need. I like to upgrade them with laser weapons then plasma as they become available (though once you have plasma you should be fitting them onto your Firestorms) but it should never take priority over your own troops or economy. The one-offs you can purchase for the little aircraft minigame vary in usefulness, but the dodging one is way too expensive to ever bother. The tracking one can come in useful for the later game scouts, and the target one I usually have a few of simply because they're very cheap and can sometimes make a difference.

Missions and Panic Level

Initially you'll get three country locations for abduction missions, the most common type of mission in the early game. Whichever country you choose will have its panic reduced by two blocks, while the other country's panic will go up two blocks. Also, every other country on the same continent as those countries will raise one block. It won't take long before you're staring down the barrel of orange and red panicked countries, so managing panic levels becomes extremely important.

When choosing missions based on rewards, always prioritize engineers early on. It's a boring reward, but since each progressive uplink requires more engineers to build, it's absolutely vital. Look into what your monthly engineer bonus is, and calculate how many more you'll need to get your next uplink. Remember that workshops provide five engineers each as well.

If you're doing well on engineers I would go money next, as $200 goes a long way in the early game. Getting an early high ranking soldier can help a lot as well, especially if you only have one of that class. I usually get offered mid-rank Assaults and always grab one. Since research speed is your lowest priority you should never take scientists if you can help it.

Sometimes, especially in the third and fourth months, panic levels will dictate which missions you take rather than rewards. Remember it's perfectly normal to lose some countries, but be selective. Try not to lose any countries that pay $100 or more, and be mindful of which bonuses you want. Also remember that whichever country you start in you automatically get the bonus, so you can ironically let the other countries on your continent withdraw. This is easiest starting in Africa or Asia where the other countries don't pay very well. You can and should also manage panic via launching satellites at the end of the month as a last resort. Regardless you're going to launch them anyway, and it's up to you whether you want to use them to save panicked countries or to get your continental bonuses earlier.

Note that the major early-midgame mission assaulting the Alien Base reduces panic worldwide, so it could be useful to try and time your Assault until the end of the month to save additional countries if needed. Also, frequently check the Grey Market after any UFO missions and especially the Alien Base mission. You should end up with a ton of damaged or useless items that you can sell. Why the game can't automatically sell these at the end of the mission I don't understand, but remember to dig in there and get yourself a few hundred bucks as a nice reward.


Squad Management

Whom you bring on any given mission is largely a personal matter depending on what is your preferred play style. That being said, I will run down each class's strengths and weaknesses, as well as which skills I prefer and finally the team combinations I like for each mission type.

The Assault

The Run 'N Gun class is your classic risk reward archetype. Think of them like a Rogue: they have to get up close and require some maneuvering, but the payoff can be huge. Interestingly, the Assault is the only class that can equip two different weapon types: the shotgun and the assault rifle. For this reason I enjoy eventually running two assaults once I reach a six person squad, one a kamikaze style with a shotgun while the second more of a tactical flanker with the rifle.

  • Tactical Sense vs. Aggression: Defense all the way, every bit helps. The shotgun wielding assault will usually have a ridiculous crit chance anyway.
  • Lightning Reflexes vs. Close and Personal: The Assaults are my flanking troops, so getting around a bunch of overwatching aliens is crucial. Reflexes can also save your life if you didn't notice someone overwatching you.
  • Flush vs. Rapid Fire: Easy choice, Flush doesn't seem to work correctly as often enough the target will just run to another cover location. Rapid Fire meanwhile you will use almost every turn you can, especially if you're performing a risky, up close shotgun blast. Causes agonizing decisions also: Go for one 70% chance or two shots at 55%?
  • Close Combat Specialist vs. Bring 'Em On: CCS is super awesome, and can allow you to obliterate chryssalids and berserkers for free as you don't even have to be in Overwatch.
  • Resilience vs. Killer Instinct: See the first skill choice. I always take defensive perks over offensive. Assaults are awesome enough, but they stop being quite so awesome when they die terribly to an awful critical hit.

Your Assault is typically getting shot at the most, as Run 'N Gun gives you a huge advantage with running around the map, flanking enemies, and scouting ahead. Always give them the health boosting items: Nano vest at first then chryssalid armor. They should always have the best armor, and eventually I like to give my close up shotgun wielder ghost armor, further reaffirming my Rogue analogy. Assaults can be amazing, but don't risk their lives unnecessarily, and always be wary of what they could reveal ahead.

The Heavy

My least favorite class by far. Heavies have poor aim and poor movement and try to make up with that by having a one-time use rocket launcher. Ignore Dr. Vahlen's comments about using explosives. By all means, use them! If you can kill two or more aliens with a blast, whip that rocket launcher out but be wary of civilians on terror missions. I never roll with more than one if I can help it. The Heavy also has the hardest choices to make when assigning class skills.

  • Bullet Swarm vs. Holo Targeting: A tough one; both are incredibly useful all the time. With Holo Targeting your Heavy becomes more supportive, while Bullet Swarm makes them more of a one man army. If you use multiple heavies, one should definitely have holo targeting to give the other a chance to hit the target. As it is, I go with Bullet Swarm and take advantage of either shoot and retreat or shoot twice.
  • Shredder Rocket vs. Suppression: Suppression is kind of interesting, essentially making a target harder to hit and getting a free hit if it moves. But it drains a ton of ammo, and in the first half of the game before you research Ammo Conservation in the Foundry, it necessitates a reload pretty much right after. If you like a supportive heavy go for it, but I use mine as walking rocket launchers, and shredder rocket gives you one more rocket to use. It does less damage but importantly debuffs all the enemies caught in the blast, so it's actually more useful in the mid and late game.
  • HEAT Ammo vs. Rapid Reaction: If only RR didn't require you to actually hit the target first, it would be pretty awesome. As I do use overwatch a lot it seems like a great choice, but heavies suck at hitting anything, and everyone gets a penalty in overwatch. HEAT Ammo is something that might not seem worth it in the early game but becomes invaluable once you're facing Cyberdiscs and the ultimate late game unit, the Sectopod.
  • Grenadier vs. Danger Zone: I like my rockets, and I use them a lot. Danger Zone lets you blow things up easier, but it can be a lot trickier not to hit your own troops in a small area. I make all my heavies carry SCOPEs to help with their awful aim, so no grenades.
  • Rocketeer vs. Mayhem: More uses or more damage? I can see the advantage of each. Without suppression or grenades however, Mayhem's usefulness diminishes so I go with Rocketeer. More rockets!

As I mentioned, equip your heavies with SCOPEs to help alleviate their terrible aim. Never move your heavies first as you never know when you need to fire off a rocket. With their terrible movement you can let your supports and assaults get around enemies while your heavies typically park behind some full cover and take potshots. Bullet Swarm can give you two shots/turn if you park them in a good spot. Don't save those rockets: as soon as you get a good chance to damage or ideally kill multiple aliens, take it.

The Sniper

Ah, the sniper. The elite assassin of any XCOM outfit. Any time spent playing the game will quickly familiarize you with how much of a killing machine a sniper can be. Your highest ranking sniper is almost always your most decorated soldier in terms of kills, and since they should always be in the back, they also have the highest survival rate. Still, my games always seem stingy about giving out Sniper designations, and you definitely want 1-2 on every mission you go on, regardless of type, so it's important to have backups in case of injury and death.

  • Snap Shot vs. Squad Sight: You might be annoyed that the sniper can't fire her main weapon after having moved. Well calm down, because Squad Sight is what you're picking, every time. Squad Sight is ridiculously overpowered as it allows a sniper to murder any alien that the rest of the squad can see, provided there's a clear line of sight. Give her skeleton armor for a higher vantage point when buildings are present, later don the amazing archangel armor and just fly up and meat out justice as an angel of death.
  • Gunslinger vs. Damn Good Ground: While it's true your sniper can and should have elevation bonuses versus her targets, she'll also need to whip out that pistol any time you reposition. You'd be amazed what at overwatching sniper with just a pistol can kill from across the map. You are giving your snipers the best pistols, right?
  • Disabling Shot vs. Battle Scanner: Your snipers are so good at alien killing that having to use them to disable one seems rather pointless. Now I'm not too crazy about the scanner either. In theory it's awesome, but since your sniper is typically playing catch up to the rest of your squad if moving at all, it only ever gets use in the very beginning of a mission, or maybe during story missions like the alien base. YMMV but I go with the scanner for those situations.
  • Executioner vs. Opportunist: You should be overwatching constantly. With opportunist your sniper will typically straight up murder any aliens that dare move within her squad sight.
  • In the Zone vs. Double Tap: In the Zone requires two things to work: 1) the target must not be in cover or be flanked by one of your soldiers (their cover symbol turns yellow) and 2) you must kill the target. You can especially mow down enemies that don't use cover, like drones and chryssalids. Double Tap, meanwhile, turns your already amazing sniper into a brutally unfair killing machine. While you can still only headshot once, you can fire twice with the sniper rifle and typically eliminate most targets. At the end of my recent Classic Ironman game, I entered the final room, fanned out ever so gently, and the turn after I revealed the boss Ethereal, took two double tapping shots with my sniper. Boom, dead Ethereal, everyone in the room dies, game won. Seriously, Double Tap, is freaking amazing.

Your snipers are your true killers. Each rank up gives them better aim and better perks. A Colonel ranked Sniper is practically a one man army, especially with archangel armor. Like the heavy, never move your sniper before other troops, you never know when new enemies get revealed and a squad sight sniper can easily kill at least one of them. Should be obvious but your snipers should always have SCOPEs. You can roll with skeleton armor if you really want to get some height advantage, but I don't like moving my snipers all that much. With archangel armor and a plasma rifle, you've pretty much already won the game. Just be wary that they are exposed up there, never just fly them around. You should always have at least one sniper on every mission, but remember to rotate at least two to have a backup. Protect your snipers, and they will win you the game.

The Support

The support is easily the most important class, as most of the perks involve making your medkits do more and get more uses. In ironman mode you'll want two supports in your squad with medkits at all times; ideally you want three so you can rotate.

  • Sprinter vs. Covering Fire: In Ironman especially you are playing much slower and careful than normal, inching along and taking advantage of Overwatch constantly. Sprinter therefore is not all that useful. The one time it would come in handy is if another squaddie falls in battle and you need to revive with a medkit. But ideally you should have two Supports at all times covering your squad.
  • Field Medic vs. Smoke and Mirrors: Field Medic always and forever. 3x medkit use is absolutely vital, with two field medic supports you've got six medkit uses, and in the end game you'll need them all.
  • Revive vs. Rifle Suppression: Revive allows you to bring soldiers back into the fight instead of just stabilizing them when they go down. During the final temple ship mission my sniper went down as I underestimated the range of sectopods. That same sniper was the one I mentioned earlier that single handedly won me the game. Your supports are your medics and they need revive.
  • Dense Smoke vs. Combat Drugs: The first real choice you have for a support. As I've mentioned several times, I always go defense over offense. Combat Drugs could prevent your squad from panicking, but the additional defense from Dense Smoke can help prevent them from getting shot at all.
  • Savior vs. Sentinel: You see Heavies, the supports totally get the better version of your Rapid Reaction skill! Still, my supports are my medics, and it allows your medkits to work better. It's a tough choice as two overwatch shots do make a huge advantage, and you should be overwatching a lot, but in the late game I typically need most if not all of those six medkit uses, and that's with savior.

Supports are your most important class to rank up, as those healing perks (especially field medic) are absolutely vital to your squadmate's survival. Your supports will probably have your worst kill-to-missions ratio, but you should run with two in every mission and rotate in backups when you can.

Team Alpha

In the beginning you have only a paltry four person squad and a bunch of rookies. Much of your initial composition will depend upon your early promotions and designations, but usually the game is pretty good about spreading out the classes. Despite my general disdain for the heavy class, their rockets can easily kill the little grey sectoids, thin men, and floaters with one blast. You'll high ranking members of each class, so go ahead and run with one of each until you get that magical fifth slot. Classic difficulty means you don't automatically start with an Officer Training School, but luckily it's not that expensive. Try to squeeze it in AFTER you've built your uplinks and satellites for that month, then go after the cheap and incredibly useful Squad Size upgrades.

At five members I like to use 2 Supports and 1 each of the rest. Since you're ignoring the main story don't jack around with the arc thrower. Give your sniper and heavy a SCOPE, your supports medkits and your assault the vest. You'll take a lot of injuries and need to rotate in rookies a lot during the early game, so feel free to use those grenades as they can offer some easy kills.

At a full six member squad your options really open up. I'd still roll with the above members, but the sixth slot could really depend on the mission. If it's a terror mission, a second assault could help your team move around better. Small UFO missions could use another sniper as there's a lot of open space to work with. Council missions full of Thin Men could use a SHIV to absorb a lot of the hits, scout ahead, and it's immune to their annoying poison. Of course it's always idea to rotate in rookies when you can, as your goal should be to have at least one backup to every member of your Alpha squad (your best team). Once you get the Rapid Recovery upgrade at the OTS (which should be the third one you buy after the two squad size upgrades), you won't have to worry about injuries near as much.

SHIVs are kind of spiffy, but they require a foundry, are reliant on upgrades, and don't gain experience. Useful in certain situations or when you're really reeling from injuries, but I never purchase more than one or two in any give game. If it's a hard mission and you're between a SHIV and a rookie, go with your robot buddy, but don't neglect your rookies completely. SHIVs do make excellent scouts as they can't use cover (and they actually provide cover for your other soldiers) and are more expendable than people. Sorry robot buddy.


Combat Tactics

All the perfect base building, detailed squad managing, and panic reducing will be for naught if you get all your soldiers killed every mission. I'm going to list a lot of general tips as with random maps and enemies the individual tactics will vary greatly from mission to mission. Remember that once you've accepted a mission you can still back all the way out to purchase another medkit or check panic levels in the situation room, etc.

  • Double check that each soldier has all the right equipment. If your star assault was injured and you used a backup, you'll need to manually swap equipment back. NEVER just buy additional equipment; it's a waste of precious money. It can be a pain, but swap equipment constantly so your away team is always using the best stuff. Note that any soldiers in PSI testing need to have all their equipment unequipped manually (assuming you need it).
  • NEVER dash unless you're moving a soldier in the back up to the frontlines. Even if you plan on dashing forward anyway (you fool!), just stop first after your first move and see if anything was revealed. Then you have the option to run into cover. If you just dash forward, you have no options (Run 'N Gun being an exception, obviously).
  • Overwatch is your friend, probably your best friend. It's best to pretend that your soldiers can only move once, then overwatch. Oftentimes enemies just off screen will run into my view, and be completely obliterated by my waiting troops. Certain perks will let some classes be absolutely beastly on overwatch.
  • Always seek full cover. You'll know it's full when the shield icon is filled in, rather than only half full. Your soldiers will get murdered in half cover. They can still get murdered in full, but at least you've got a fighting chance. Note that the sniper perk Low Profile lets your snipers use partial cover as if it's full.
  • Flank enemies when you can. Flanking means that you position your soldier to where the enemies' cover is no longer between you two. Look for when the cover shield symbol turns yellow. Assaults are best at flanking since they can Run 'N Gun and quickly move around the map, but be careful not to reveal additional enemies or you'll have all new problems.
  • If there's only one enemy in a specific area left, use that shotgun toting assault to run right up next to it and blow its face off. It's both satisfying and much better than trying to trade shots back and forth.
  • Speaking of trading shots, don't do it. On Classic the aliens will usually prevail (and usually always find full cover). It will be necessary at times but don't prolong it and always have a plan, even if that plan is just to retreat and overwatch.
  • PSI abilities can be very useful; it's a shame you get them so late in the game. Even just mindfray can come in very handy as you'll typically be faced with a 70% chance to shoot but 90% chance to mindblast and do a solid five damage. It's important to note that the only way to advance your psi abilities is to use them, and you need a max ranked psi soldier to approach the final mission. The second tier of psi abilities is largely a matter of preference, but for the third tier I love mind controlling the aliens and using them against each other, or as scouts.
  • A panicked soldier is a scary situation, but hopefully manageable. On Classic soldiers panic much more often, but typically fire at the aliens first. As they rank up and you get the Iron Will upgrade, panic will generally become a thing of the past until someone dies in front of them.

Know Thy Enemy

            Sectoids - Killing the one doing the mind controlling will result in a double kill, as the one being mind controlled will always die from the feedback. That can be tricky though, as the controller likes to stick to the back. With such low health, the grays are perfect for grenades.

            Thin Men - That poison can be awful, and what's worse it tends to set off a chain of panic. Don't underestimate them. You'll continue to see Thin Men even into the late game as they appear en masse as the exclusive enemy during council missions. They tend to bunch up and usually spawn in threes, perfect for a rocket.

            Outsider - Only found in UFOs early on, the outsider is important to the story as you need to capture one "alive" with the arc thrower. Don't feel pressure to do this any earlier than you feel comfortable. You should already wait a few months to even build the arc thrower and containment lab. Since you know where they are in any give map, take care to not approach the UFO until you're ready to deal with it, ideally as the final enemy left.

            Floaters - They have an annoying ability to magically float up into the air and reappear right behind your sniper, but thankfully it takes them a full turn to accomplish. Murder them for it. They get a constant elevation bonus but don't use cover, so quickly kill them before they can flank you.

            Chryssalids - Ugh. UGH. Chryssalids can absolutely ruin your day, and your playthrough. If you get a terror mission early on with nothing but chryssalids, I think you're just screwed. Hopefully you only ever have to deal with a handful. Do not under any circumstances let them get near you, and realize that they can always move much farther than you think. Retreat and use overwatch, or if you can kill them in one turn, rush them and plant some shotgun shells into their chitinous body. Rockets can work wonders as well, but as you usually encounter them on terror missions, be wary of friendly fire.

            Zombies - Kudos for Dr. Vahlen for actually calling them what they are - that always bugs me in every zombie fiction ever. Anyway, where there's chryssalids there's bound to be a zombie or two as they transform the civilians you're supposed to save into a whole new enemy. Despite the slow animation of their gait, zombies can move surprisingly far and do a ton of damage. Treat them just like chryssalids, but prioritize their progeny first to prevent more zombies from rising.

            Mutons - The first real game changer, the Muton comes equipped with a plasma rifle, alien grenade, and blood call ability. The first time you encounter them expect to take heavy damage and probably some losses, as they usually come in groups of three and have enough health to take a couple successful hits to down. If you group your soldiers up they will use their grenades, so make sure your troops always have more than five health. Flank them when you can but don't risk your soldier's life doing it, and whatever you do, don't reveal any new areas to add new enemies to the fight.

            Drone - Small and weak, the drone's real threat is as a healer to nearby Cyberdiscs and sectopods. You can try to capture them yourself using an arcthrower, but seeing as how they're usually near these formidable enemies I never mess around with that. Should target them first unless you can kill their bigger ally in one turn.

            Cyberdisc - A frightening enemy when you first see it transform, the CD has impressive flying movement but doesn't seem to move around near as much as floaters do. They do come equipped with an alien grenade, and up close can perform a powerful AOE attack. Perfect fodder for snipers and HEAT heavies. Try not to use a shotgun assault to deal the final blow, as they create a small explosion when slain.

            Berserker - You might be wary of their beefy health, but they don't move near as much as the dreaded chryssalid. You'll quickly learn that every time you attack, it gets some bonus steps to close in on its attacker. Use this to your advantage to draw it into your waiting troops. Perfect for finishing off with the arc thrower as well.

            Sectoid Commander - Kill as quickly as possible, as they will mostly mind control one of your squadmates on their first turn. Luckily you usually encounter them at the end of a UFO, in their own little room, so you should have everyone ready to burst into that room and unleash hell. There is no excuse to let them live long enough to use your own troops against you.

            Muton Elite - Beefier but otherwise unchanged from normal Mutons. You should have high ranking troops with plasma weaponry, so they should be much easier than when you first saw Mutons

            Heavy Floaters - Same as the Muton Elites, just a straight upgrade healthwise. Double Tapping snipers should down them easy.

            Sectopod - The first new alien threat to give you pause in the late game, the hulking bipedal sectopod can fire two shots in one turn, including an AOE volley attack and a devastating laser blast that if it misses, will destroy any cover you're cowering behind. They are classified as robotic enemies, though, so make sure your HEAT heavies are firing on them and racking up the damage. I believe Classic mode allows them to fire twice without having to first paint their target like on Normal mode, as I'm pretty sure they weren't nearly as devastating on normal. Like the CD, kill any drones first or they'll just heal it.

            Ethereal - Pretty much an upgrade to the Sectoid Commander, as these mysterious beings will also like to mind control your troops. Like the commanders, you'll typically encounter them in their own room in a UFO, but they could easily have a Muton or two along as guards. Feel free to be overly aggressive in these final rooms and take out that Ethereal before it can wreck havoc with mind control.