XCOM 2

Each new game starts you on March 1st. The goal of this achievement is to beat the game on Commander (or Legend ) difficulty in under four months. You will need to plan out your research and construction goals, ignoring most upgrades in favor of the mission critical projects.

I thought it might help people to see a sample timeline. This is a log of my activity with the exact days that I completed each of the important research projects, construction projects, and missions along the critical path. I played on Commander difficulty and chose to simultaneously obtain the achievements for never buying a squad size upgrade and the achievement for never losing a soldier. This didn't end up being much of a handicap at all. You won't have much time to spare on building a GTS school and you certainly can't be spending time training new soldiers to replace the fallen.

I ended up finishing all of the critical projects and missions with about 10-15 days remaining. I took my foot off the gas a bit in month four to spend time researching additional armor and weapon upgrades, as time allowed.

I'm sure there are dozens of ways to approach this achievement and your results may vary. That being said, I am sure this type of outline will prove useful to a number of people.


Month 1
March 05 - Lab Research Completed: Alien Biotech
March 07 - Staffing Update: Eng (2)
March 10 - Lab Research Completed: ADVENT Officer Autopsy
March 14 - Staffing Update: Sci (1)
March 21 - Mission: Investigate Blacksite
March 22 - Construction Completed: Proving Grounds
March 30 - Proving Grounds Project Completed: Skulljack

Quick Tips For the Month:


Month 2
April 05 - Mission: Skulljack an ADVENT Captain / Kill Codex
April 06 - Lab Research Completed: Alien Encryption
April 12 - Discovered Black Market
April 12 - Staffing Update: Eng (3)
April 15 - Lab Research Completed: Magnetic Weapons
April 18 - Construction Completed: Shadow Chamber
April 19 - Staffing Update: Sci (4)
April 25 - Shadow Chamber Research Completed: Blacksite Vial
April 28 - Lab Research Completed: Resistance Comms

Quick Tips For the Month:


Month 3
May 02 - Shadow Chamber Research Completed: Codex Brain
May 05 - Construction Completed: Resistance Comms
May 10 - Mission: Investigate Blacksite Vial Coordinates (The Forge)
May 13 - Shadow Chamber Research Completed: Codex Data
May 18 - Mission: Skulljack Codex / Kill Avatar
May 22 - Shadow Chamber Research Completed: Stasis Suit

Quick Tips For the Month:


Month 4
June 01 - Mission: Investigate Codex Brain Coordinates (Recover Psi Gate)
June 11 - Shadow Chamber Research: Research Psi Gate
June 20 - Lab Research Completed: Plated Armor
June 24 - Shadow Chamber Research: Avatar Corpse Autopsy
June 27 - Mission: ADVENT Network Tower
June 27 - Mission: Alien Fortress

Quick Tips For the Month:


You may have noticed I didn't mention the AVATAR tracker once. It shouldn't become an issue. You're rattling off main missions frequently enough to keep it in check.

As for combat:
This guide is primarily focused on the top level strategy. There are lots of people out there willing to give advice on higher difficulty combat. Most of it boils down to knowing your classes, staying in cover, and doing a lot of your damage from overwatch. Hang back and let the aliens spend their actions on movement. You spend yours on shooting.

Just don't forget, this isn't ironman. Save early and often. I saved just about 200 times on this run alone. Always try for the low chance outcomes that allow you to keep your soldiers from getting injured. I completed 19 missions in the four months and 12 of them were flawless. Keep this in mind. Prioritize weapon upgrades over armor upgrades. You don't need to spend resources on armor upgrades if you're never going to let yourself get hit.

Thank's for reading and good luck commander.

There's nothing wrong with the other solution; I just thought I'd give another take on it, with some of the same tips and some different ones.

1. To unlock this achievement, you must have a near-perfect game, meaning you have to make all the right choices about building facilities, performing research, scanning with the Avenger, and, of course, you have to be flawless on the battlefield most of the time. This means you WILL be abusing the Start Menu to save and load your game progress. If one of your lead soldiers gets wounded, even slightly, you'll usually need to reload and try something different. I know, it can feel like a cheap way to win, but it's actually a very strategic challenge of its own kind, and will take all the XCOM skills you have. If a top soldier has to miss even one battle, things could go south, and even if they don't, that soldier might miss out on getting promoted all the way to colonel by the time of the final mission.

With the above in mind, plan on getting
in the same playthrough.

2. Game setup: Choose Commander difficulty, no Ironman. If you have the Alien Hunters DLC installed, DO select it (as in, put a checkmark next to it). If you don't, you'll have to fight all of the alien rulers, and you don't have time for that. If you select it, you'll have to scan for the unique weapons if you want them, but then you don't have to deal with the rest of that DLC. I would leave Shen's Last Gift unselected. That way, you can build a free Spark in the proving ground without having to play the mission. (I didn't enable the tutorial because that automatically fails you for The Untouchables achievement.)

3. You should have auto-save turned on in Options->Gameplay. (It's on by default.) This will save your butt over and over. The game auto-saves just before the beginning of your turn, which means you get to see the results of your turn and then watch what happens on the aliens' turn. If something bad happens, then before your next turn begins, simply go to the Start menu, load your last auto-save (or 1 or 2 saves back), and you're back at the beginning of your turn.

4. Also use manual saves frequently. Trying to control a sectopod or skullmine an Advent? Save first. Trying to take down an archon with a Deadeye shot from your sharpshooter? Save first. Was the hack sucessful? Did you make the shot? If so, save again. Again, I know some players may be turning up their noses at this advice, but do you want to unlock the achievement or not?

5. As for commanding the Avenger, engineers, especially early on, are EVERYTHING. Once you finish the gatecrasher mission, go to the research lab and the engineering lab, then SAVE. Press Y to go to the bridge and see what it gives you to scan. If it isn't an engineer, reload. I'm serious about engineers. You should get 4 or 5 as quickly as you can. Scientists are also important, but you can wait a little while before collecting them. Don't wait too long, though, because there will be a point about 2/3 of the way through where you MUST have at least 4 scientists to proceed. You will typically get enough intel and supplies from missions. Remember that if you have a specialist who does a lot of hacking and skullmining, you can get extra intel and supplies that way.

6. You'll need to rush building the Shadow Chamber much quicker than you normally would. I completed mine on April 20, and I just barely had time to finish the game (1 day to spare). You'll also need to stay on top of Resistance Comms and power. Those three things - Shadow Chamber, Resistance Comms, and power, can bring you to a dead stop, and you can't afford that. The other facilities, like the Advanced Warfare Center and Guerilla Training Center, are nice-to-haves, but not having them won't bring your objective progress to a dead stop.

7. I made three tries at this achievement and was never able to get the Defense Matrix built in time to do me any good, so you should probably pass on that. The Psionic Lab is out of the question. You won't have time to even research psionics, much less build a lab and train soldiers. All of the other facilities are doable. For the record, my facility completion order was workshop (March 16), power relay (March 25), proving grounds (April 3), resistance comms (April 5), shadow chamber (April 20), advanced warfare center (April 21), guerilla training school (May 9), second power relay (over coil, June 13), laboratory (June 28). I don't know whether going for the workshop early was the best way to go, but it worked for me.

8. Ignore the alien facilities and the Avatar counter. The aliens won't finish the Avatar project before July 1 as long as you complete your objectives on schedule. (They obviously didn't hire enough ENGINEERS .) Go on all of the time-sensitive missions (guerilla ops, supply raids, etc.) Only attack an alien facility if you have some time to spare at the end and want to see if you can get your soldiers ranked up.

9. Except for maybe your home continent, you probably won't have time to go for continent bonuses. Sorry.

10. Other than the region contacts and radio relays that you need to progress in the game, the only scanning you should do in the Avenger out in the world is for engineers, scientists, Avenger power, comms, and the monthly supply drop. Any other free time you have in the Avenger should be spent back at HQ on Rapid Construction. You won't have a whole lot of chances to do that, but take advantage of them when you do.

11. Keep a calendar somewhere - on your computer, on a whiteboard, or whatever - of your game progress. That way, if you miss the deadline, you can reload from where you think things started to go wrong instead of having to start a whole new game.

And, last but not least ...
12. The achievement should really be worded "Beat the game on Commander+ difficulty before July 1st" or "by June 30," because if you begin the final assault on July 1, you'll get a big fat nada. STATUS CONFIRMED.

INFINITE TURN GLITCH.
Works in base game only, it does not in War of The Choosen.

Achievement is quite easy with infinite turn glitch. This glitch works in standard and Ironman playthrough, on any difficulty.
To make it work you have to save game short before you finish last move of your last character after which normally enemy would have his turn and then load that save. You will still have your turn while enemy looses his.
Just be carefull with few exceptions, enemies who transforms from other forms or pop up can still make their move so watch out when you want to trigger them - this applies for Andromedons, Chryssalids and Faceless.

Using this glitch you can even go for all below achievements in same playthrough:









And do another playtrough for Legend as it has larger times and cost required for all research and constructions and there is no way you can beat game on Legend by July 1st.