The XCOM franchise isn't known for pulling punches, and XCOM 2 is no different. This turn-based tactical game is a meat grinder, and the soldiers you throw against our alien occupiers just happen to be both your most valuable and your most vulnerable assets.
Without skilled troops, humanity is doomed, so here's my best tips for keeping them alive.
Lesson 1: The art of the ambush
XCOM 2 introduces a new mechanic called concealment. Most of the time when your troops enter the battlefield, the aliens won't react to them right away. So long as you stay outside of their field of vision, you can maneuver without drawing aggro.
But the aliens will react to the sound of your troops moving, eventually zeroing in on your location. If you stay in one place, best-case scenario is that you've got three turns before the aliens reach you. That means that if you're quick you can slip right past them, but it's much harder than it looks.
Often the best course of action is to plan a hasty ambush.
I like to use my grenadier to kick things off, launching a grenade into a cluster of enemies and doing as much damage as possible. But it wouldn't be a bad idea to use a sharpshooter sometimes — especially at higher ranks.
For best results, stage the rest of your squad with good lines of sight into the kill zone. Have a few in overwatch, ready to fire when the aliens take cover. But also keep a few actions in reserve. Your percentages to hit are much higher when you're not taking a reaction shot, and special abilities often do more damage than a standard attack.
Once you've dealt with that first cluster of enemies, don't expect the rest of the aliens on the map to come running. But once you uncover them, once they step out of the fog of war, you'd best be ready for a fight.
Lesson 2: Don't hack everything you see
Thanks to the specialist's drone familiar, if you can see it you can hack it. But don't go crazy. Blowing a hack can lose concealment and sometimes even call in reinforcements.
My personal preference is only to attempt hacks once concealment is lost, and even then I only attempt hacks on robots and turrets. Towers are just too risky.
Lesson 3: Know when fold 'em
When your troops are being overwhelmed, sometimes a tactical withdrawal is the best option. Unlike previous iterations, getting to the choppa has never been easier than it is in XCOM 2. Just hit the button in the upper right-hand corner of the screen and call down Firebrand to pick you up.
Making things even more interesting, roping out of the combat zone is a free action. All you have to do is get your troops inside the nine-square grid and hit option three on the action bar, and they're out of harm's way.
Most of the time, once you've secured the mission objective you'll be assigned a new task: Kill all the aliens on the map. But if the objective is portable and your troops are starting to get picked off, there's no shame in cutting your losses. Get the goods into Firebrand — along with whatever troops are still standing — and get out of Dodge.
Lesson 4: Keep moving forward
Nearly every mission in XCOM 2 has a timer, and nearly all of those timers require your troops to be in the right place before the clock winds down.
The only solution for being on time and on target is to keep moving forward. But there's always a trade-off. Take one step too far and you run the risk of alerting the next group of enemies and bringing more heat on yourself than is manageable. This was sort of a nightmare in XCOM: Enemy Unknown, but in XCOM 2 it's much more manageable and — dare I say it — fair.
But it's still a danger.
My rule of thumb is to always "leapfrog" forward, only moving soldiers up through my front-line when I have actions available to use to cover them. If those new front-line soldiers encounter an alien while pushing back the fog of war, I can use my other soldiers' actions to pin the enemy down, destroy them or force them to move.
But sending a soldier forward when unsupported may at times be the only way to achieve your objective. That's why XCOM 2 is hard.
Remember that there are certain skills granted to the ranger class as they rank up that allow them to re-enter concealment. Don't forget to use those skills to scout forward when you have the chance.
Lesson 5: The Proving Grounds are your friend
The Proving Grounds are an exceptional way to upgrade your firepower. The incremental boosts it gives you, especially in the early game, are invaluable for bridging the gap between conventional, magnetic and later plasma weapons. But there's a twist.
You'll be able to research experimental munitions, but you're not always guaranteed what you'll get. My recommendation would be to start with experimental grenades, and hope and pray you end up with acid grenades. The lingering damage they do is especially useful against vipers, and in the later game against melee enemies.
Lesson 6: Get in their heads
The opportunity to field psionic soldiers is granted fairly early in the game, but in order to get them on your roster you've got to train them up. And that means building a Psi Lab.
Unfortunately, the Psi Lab lingers at the bottom of the facility build list. It's easy to miss, month after month, because you'll have plenty of other priorities — like expanding your network of resistance contacts. I went most of the way through the game before spooling up my psionics program, and I wish I hadn't waited so long.
Make the commitment of resources, assign an engineer to help with the training regimen, and get in their heads early.
Lesson 7: STEM fields are the future
Engineers are more than just numbers in XCOM 2. They have a name and a face, and a unique role to play this time around.
As you expand the XCOM mobile base you'll add new facilities. It's not explicitly stated in the tutorial, but it turns out that each of these facilities can be staffed by one or more engineers. The more staff you add to each room, the bigger the production bonus you'll receive. Putting engineers to work in the right place can increase the number of resistance cells you contact, goose your power output or even speed up the recovery of your injured soldiers.
Lesson 8: Unconventional warfare
Traditionally, XCOM operatives work well as an interdisciplinary team. A sharpshooter keeps a ranger safe from a distance, while a grenadier minds the midfield and the specialist keeps everyone healthy. But the skill trees available for each class make it clear that there's more than one way to build a soldier.
A ranger can be a stealthy blademaster, or a fleet-footed grunt with a trench gun. A sharpshooter can be a long-range marksman, or a deadly short-range gunslinger.
The next time I play through XCOM 2 I'm going to try and build out a few trick squads, composed entirely of a single class of soldier. Each one will be a variation on a theme, a specialized specialist.
I'm not trying to make the game harder on myself, so these trick squads aren't just for the challenge. At a certain point you develop the ability to ascertain what kinds of aliens will be waiting for you on a mission, and it would be interesting to see if specially designed squads would be useful in given situations.
Lesson 9: It's all about logistics
Money goes fast in XCOM 2, and so do resources. Keep your personal goals in mind before you go on a spending spree at the beginning of the month. If you want to build a particular set of armor, for instance, you're going to need the supplies to do it. So don't go spending everything on weapons.
Part of the joy of XCOM 2 is being pushed from place to place around the map and never quite knowing what's going to come next. That means you could be pretty far from your next meal of intelligence or supplies and never know it. That's why it's best to save for a rainy day.