Army of Two: The 40th Day Achievement Guide & Road Map

Army of Two: The 40th Day
Army of Two: The 40th Day Achievement Guide

Overview:
- Estimated achievement difficulty: 4/10(With Boosting) 8/10(Without Boosting)
- Offline: 800 + 250 (DLC)
- Online: 200
- Approximate amount of time to 1250 : 40+ hours
- Minimum number of playthroughs needed: 2
- Number of missable achievements: Humanist, Heartless, and Purist
- Do cheat codes disable achievements?: No cheats.
- Does difficulty affect achievements?: Yes. Softcore, Hardcore, and Unbreakable.
- Glitchy achievements: All DLC achievements (See Step 5)
- Unobtainable achievements: None
- Extra Equipment Needed?: Boosting partner

Introduction
I have given this game a 8/10 because of the online achievements. The online service is pretty shabby and has a lot of connection issues, which can negate achievement progress. Due to this it often makes the achievements hard to get and can be quite frustrating. There are no glitches but the achievement criteria can be a little unclear, but the achievement guide will detail everything for you. Owning the previous game in the series 'Army of Two' and having a valid save will unlock the AS-KR1 and Sniper Launcher for purchase in The 40th Day.

Helpful Links
Achievement Trading Thread
Create A Mask FAQ
Guide To Starting Your Own Lobby
Collectible List

Step 1 – Lowest Difficulty + Positive Choices + Saving Hostages + All Collectibles
For the first step you will be playing on the lowest difficulty and making all the positive morality choices, whilst saving the hostages and obtaining the radio’s, the weapons and weapon parts and the Maneki Neko cats. In the achievement guide there is a combined list of all the collectibles (Cats, Weapons and Radio’s) and also a list of all the hostages. At some point in each chapter you are given a morality choice, in this playthrough you should make positive choices and must make positive choices all through this playthrough. Providing you have followed all the collectible lists and saved all of the hostages, you should be on a minimum of 230 , but you will pick up some other miscellaneous achievements along the way.

Step 2 – Contractor Difficulty + Negative Choices + Good and Bad friendship
For this step you will need to play through the game again but be on Contractor difficulty. Also note that if you are playing with a friend you must both be on Contractor difficulty. Similarly to Step 1, in Step 2 you will be given the same morality choices, but this time you must choose the negative or ‘bad’ ones.

Step 3 – Future Visions + Full Arsenal
To get the future visions achievement you must play as the opposite character that you played with when you done the first playthrough. Then just load the last chapter and get to the end of the game and then choose the option to shoot your partner.
For full arsenal you must buy every weapon and every weapon part. Assuming you have followed everything correctly up to this point then all you need to do is purchase the weapons.

Step 4 – Mop up Single Player + "The Beast"

There are dozens of miscellaneous achievements in this game which mainly require you to kill enemies in a certain fashion, kill them with a certain weapon or even play rock, paper, scissors. Most of them will unlock without you trying for them too hard but each achievement is explained in detail, in the achievement guide. Now it’s time to grind out The Beast achievement and kill thousands of enemies. Don’t be put off though as there is an easy place to get it as pointed out in the guide.

Step 5 – Chapters of Deceit Downloadable Content Pack
Chapters of Deceit is the only content pack for Army of Two: The 40th Day, the add-on has eight new achievements totaling 250 and costs the standard 800 Microsoft Points. The achievements can all be gained offline in single player mode or online/split-screen, it’s entirely up to you. Depending on what achievements you have unlocked from the original retail disc, it is a possibility that all of the Chapters of Deceit achievements could be severely glitched and not unlock for you.

*Avoiding the glitches – Important Please Read*
The achievements tied to this DLC pack will not unlock if you have already gained an achievement which requires an online connection from the retail disc. The ratio of the achievements not being unlocked is 1:1, this means if you have unlocked an online achievement then one achievement from the DLC pack will not unlock, the achievement that will be glitched will be random. In the same vein if you’ve unlocked six online achievements then six achievements from the content pack will be rendered useless and unlockable. With that in mind let’s get on to the achievement hunting.

The Chapters of Deceit content pack adds two new levels to the campaign and no achievements are technically missable as you can replay the chapters/checkpoints. There is an alternate ending and there are two achievements related to this, one for saving Meilin Ju and the other for killing her. These achievements are Good Fellas and Good Guys, you will know when you reach this part as it is the only point where you have to make a decision. I would suggest that you pick any decision and then when the achievement unlocked pause the game and reload last checkpoint, then choose the opposite decision and you should have both achievements, and now continue with the game.

Five of the last six achievements are story related and cannot be missed, the only achievement you need to watch out for is Men of the People, in which you need to save all the hostages. See the related achievement in the guide for details. The rest of the achievements will unlock when you finish protecting Dr. Wu, find a new mask, Kill Jonah and finish each chapter.

Step 6 – Multiplayer Achievements
At this point you should be at around 20 hours of gameplay and have most of the achievements under your belt. This is the last part and is the most time consuming and irritating. To survive in multiplayer you must use teamwork and as many people in the online community do not want to cooperate or speak then your best bet is going to the achievement trading thread and finding a member from this site, or even a whole boosting group. See the Helpful Links at the beginning of the Roadmap to find boosting partners and a guide on how to start your own game lobby.

Conclusion
There are only three missable achievements which are "Heartless", "Purist", "Humanist". Failing to get these achievements in one playthrough means you will have to play through the whole game again, sorry folks. Apart from that there are no other missable achievements but if you are missing any you can always reload certain chapters and the online service is always there.

x360a would like to thank Agent Aero for this road map

Not What I Thought It Was

5
You need to complete Chapter 1 on Any Difficulty Level
(11)
See Hardcore
A Steep Descent

10
You need to complete Chapter 2 on Any Difficulty Level
(6)
See Hardcore
A Decent Animal

15
You need to complete Chapter 3 on Any Difficulty Level

See Hardcore
Emergency Room

20
You need to complete Chapter 4 on Any Difficulty Level
(3)
See Hardcore
Gone Shopping

25
You need to complete Chapter 5 on Any Difficulty Level

See Hardcore
Survivor?

30
You need to complete the Game on Any Difficulty Level
(3)
See Hardcore
Softcore

50
You need to complete Half the Game on Contractor Difficulty
(2)
This will unlock towards the end of chapter, soon after freeing the zoo keeper.
Hardcore

100
You need to complete the Game on Contractor Difficulty
(29)
As stated in the descriptions, just complete each chapter and you will earn the achievement. Completing a game on casual and then reloading the last chapter and finishing on contractor will not get you this achievement. Also both players must play on contractor.
Meat Bag

15
You need to use 15 enemies as human shields
(4)
Just get close to an enemy and hit , if done correctly you will be able to walk around using the enemy as a shield. You can check how many of these you have by going into the start menu and going to statistics then looking for "Human Shields Used".
Chaaaaarge!

15
You need to charge through 20 enemies
(6)
Get a little distance from the enemy and hold down and run directly at him. You can check how many charges you have by going into the start menu and going to statistics then looking for "Enemies Charged".
The Beast

50
You need to kill 6,666 people in Campaign
(16)
This obviously counts through all of your playthroughs and will take you about 5-7 total playthroughs to get this many kills. You could potentially find a spot with a lot of enemies and just keep killing them, and reloading the checkpoint (it will save your kills regardless of hitting a checkpoint or not). You can check how many kills you have by going into the start menu and going to statistics then looking for "Enemies Killed".
Grenadier

10
You need to kill 3 or more enemies with a single grenade
(2)
Later on in Chapter 1 you will come to your first hostage situation, you will come to a cut-scene were they explain “Civilians” and how to rescue them. Just have your co-op AI or real partner go up to the first guy and take him hostage. Then Tie Down the other 2 guards. Now they will be laying in a circle on the floor, toss a grenade in the middle. You will probably kill the hostages so just restart the checkpoint.

You can also use a grenade launcher to help get this later on in the game. You can check what your highest grenade kill is by going into the start menu, going to Statistics and looking for "Most Kills With A Single Grenade".
Pistolier

20
You need to kill 150 enemies with a pistol
(3)
Just use a pistol and you will get this over time, you can check how many kills you have with each weapon by going into the start menu and going to statistics.
Old Faithful

20
You need to kill 400 enemies with assault rifles, sub machinguns or shotguns
(1)
Just use these weapons and you will get this over time, you can check how many kills you have with each weapon by going into the start menu and going to statistics.
One Shot, One Kill

20
You need to kill 100 enemies with a sniper rifle

Just use a sniper and you will get this over time, you can check how many kills you have with each weapon by going into the start menu and going to statistics.
Quick Draw

15
You need to kill 25 enemies with a quick draw from mock surrender
(3)
Sometimes when you come up on a group of enemies it will give you an option to hit to enter "mock surrender". Once in mock surrender mode you can either tap again to buy more time and drop to your knees or hit to do a quick draw. You can still do a quick draw if you drop to your knees. Use to aim. You can keep reloading check points near one of these places if you want to get them quicker.
Open Hand Slap!

15
You need to kill 50 enemies with a melee or bayonet
(1)
Use the button to melee and kill an enemy. You can check how many melee kills you have by going into the start menu and going to statistics.
Unbreakable

25
You must survive an entire level in one session without being downed on normal difficulty or above
(5)
This is easiest on chapter 1 on normal difficulty. This isn't very hard if you go slow, stay behind cover until all of the enemies are dead and use your Agro along with good communication with your partner.

You cannot use "restart checkpoint"!
Not So Bad After All

10
You need to tie up 15 enemy combatants instead of executing them

You can get these in hostage situations or by running up to enemies and hitting and then pushing in to tie them up. If playing through normally you should have this or be very close by the end of chapter 2. You can check how many you have by going into the start menu, going to statistics and looking for "Enemies Tied Down".
Healer

10
You need to heal your partner 10 times
(3)
You will get this playing with a partner, just run up to a downed player and hit to get them back up. You can also just personally down your partner, them get him back up, repeat 10 times. You can check how many you have by going into the start menu, going to statistics and looking for "Number Of Times You Saved Your Partner".
Co-Op Sniper

10
You need to Co-Op Snipe 5 enemies
(2)
This is different from the 1st Army of Two, all you have to do is be snipping at the same time to be in co-op snipe mode. You can check how many you have by going into the start menu, going to statistics and looking for "Co-op snipes".
Attention Grabber

10
You need to allow your partner to snipe 5 guys while in Mock Surrender
(2)
Go into mock surrender by tapping when given the prompt and just let you partner snipe as many guys as possible. He may need to attempt this a few times to get 5 kills.

Easy method for solo...load up chapter 4 (start) and have Rios/Salem advance (up on d-pad) to the corner and have him stop (right on d-pad) now sprint up you'll see people running there is a yellow washer machine here (black cable next to it if you didn't see it right away) duck in to cover here stay put let the guard the ground take a step forward before coming out of cover (if you don't do this they'll just fire on you) ease out and go in to mock surrender Rios/Salem will target the guy on the ground you shoot the guy in the turret. Restart checkpoint.
In Synch

10
You need to kill two enemies with simultaneous Quick Draws while in Co-op Mock Surrender
(5)
Go into a Co-op Mock Surrender by being close to your partner and hitting A when prompted. You both need to get a 1 shot quick draw kill at the same time. Counting down to your partner helps with the timing. You can also still aim by using .

This video is on chapter 5 - A Shattered City
Pumpkin Patch

10
You need to shoot 2 enemies in the head with a single bullet
(8)
In the same place as Grenadier, again have your co-op AI or real player take the first guy hostage. Then pull out your sniper and walk over to the guy on the left, they will all drop to their knees, just line-up 2 of their heads for an easy double headshot.
Total FistBump Destruction

10
You need to finish the game as best friends
(4)
To get this you must finish the game with a partnership camaraderie level of "Ambiguous ...". You can check this by hitting the START button and looking under "Partnership" in the bottom left corner. As long as at the end of chapter 7, right before you plant the C4 and enter the room, your partnership status reads "Ambiguous ..." then you will get the achievement. There will be some random word after ambiguous but that doesn't matter.

When not in combat, go up to your partner and hit to give him props, this will increase your camaraderie. Stand outside the final C4 door in chapter 7 and hit over and over again until your status is correct.

To get both of these in 1 playthrough
After you open the final door by placing C4 on it, you will be asked to make one last decision. Make your decision, watch the cut scene and now the mission review will appear. After you hit A on the mission review screen press and reload last checkpoint. You will have to do the battle on the stairs again. Once that is complete just keep tapping or near your partner to change your camaraderie in the opposite direction.
Total Fistbump Deflation

10
You need to finish the game in a fractured friendship

This is the exact opposite of Total Fistbump Destruction. Instead of boosting camaraderie you need to decrease it. Do this by hitting the near your partner while not in combat.

You need to finish with a final partnership camaraderie level of "Hateful ...". Again, any words after the first word are irrelevant. Stand outside the final C4 door in chapter 7 and hit over and over again until your status is correct.
The Truth Is Right Here

20
You need to listen to all of the Radio Broadcasts

There are 14 radio broadcasts. These carry over between playthroughs. You don't actually have to listen to these, just find them. You can check this by going to the start menu, going to statistics and looking for "Radios Found".

See the videos in Full Arsenal
Loot and Pillage

20
You need to collect $1,000,000
(4)
Assuming you have found most of the money stashes, saved the hostages, etc... you may or may not get this on your first playthrough. I was about mid way through chapter 7 when it unlocked.

Any money earned is lost if you don't reach the next checkpoint. For instance, the 25k at the end of chapter 2 will only stay in your account if you finish the mission, if you're killed it will disappear from your account and you'll have to grab it again. Also, you will only get the money from the big piles that are lying around once, but the money from supply crates will count every time, as will the money for objectives.

Feel free to spend your money, the achievement will pop when you have earned $1 million across all playthroughs. You can check this by going to the start menu, going to statistics and looking for "Total Money Found".
Full Arsenal

30
You need to collect All Weapons and Weapon Parts
(13)
There are 15 weapons parts and 2 more inside of supply crates.

In order to get this achievement you will need to...
- Play through entire campaign making only positive choices
- Play through entire campaign making only negative choices
- Save all the hostages
- Find all the weapons parts
- Buy all the weapons
- Buy all weapon attachments (minus the styles)
Note: There are 2 guns that will only unlock if you have an original Army of Two game save, you do NOT need to have these guns for the achievement. The 2 guns are the AS-KRI and the S8-Z "Grand Pinger".

Note on chapter 1 video
I forgot the 1st supply crate that holds a weapon part (G14 Thunderstrike). Until I can redo the video, its location is in chapter 1, after your first decision and after you kill 3 enemies.

Chapter 1 - Collectibles Video

Note on chapter 2 video
Reducer & enhancer names are switched around in the video.

Chapter 2 - Collectibles Video

Chapter 3 - Collectibles Video

Note on chapter 4 video
On your positive moral playthrough make sure to grab the G18C pistol. This can be found on the hospital level when the Doc opens a door to a weapons rooms but this only happens if you have made positive moral choices up to this point.

Chapter 4 - Collectibles Video

Chapter 5 - Collectibles Video

Chapter 6 - Collectibles Video

Chapter 7 - Collectibles Video
Touch Not a Cat but a Glove

50
You need to shoot all Maneki Neko cats in the game
(9)
There are 12 cats. These carry over between playthroughs. You can check this by going to the START menu, going to statistics and looking for "Lucky Cats Eliminated".

See the videos in Full Arsenal
Hate Monger

10
You need to customize a weapon to high aggro

Easiest way is to buy the RPG and customize it with Pimp. The achievement will pop after you purchase the upgrades.
The Optimist

5
You need to make a positive coop morality choice

See The Pessimist
The Pessimist

5
You need to make a negative coop morality choice

Shortly after you start chapter one and complete some training you will be asked to make your first morality choice. Pick A to let the guy live and you will unlock The Optimist. Pick B and you will unlock The Pessimist. Right after the achievement pops you can hit start and “restart from checkpoint” to unlock the other achievement. You will start very close to this spot.

Note: Just make sure to stick with whatever decision you picked last for the rest of your morality choices throughout the game so you can unlock either Heartless or Purist.
Humanist

30
You need to save every hostage
(13)
You have to save all of these hostages in 1 playthrough, reloading the chapters after you completed the game will not work (reload the checkpoint if you fail to save a hostage). You will know when you need to save a hostage because there will be a small cut scene showing you the hostages and the enemies (with the exception of the 3 listed above). There are basically 2 different ways to do all of these hostage situations. Method 1, Gunz-a-Blazin! Method 2, Eye for an Eye!

Gunz-a-Blazin is to just kill all of the enemies as quickly as possible, starting with the guy or guys who are the biggest threat to the hostages. This works well when the enemies are bunched together and few in numbers.

Eye for an Eye just means, they have a hostage so you take a hostage. If your hostage is a superior officer over the other enemies, they will put their hands in the air and surrender. To check their ranks, hit . To grab a hostage, sneak up behind him and press .

If you mess up and a hostage dies, just immediately reload the last checkpoint. It tells you at the end of each chapter how many hostages you saved. Every hostage has an ID card, viewable in the start menu.

This will unlock in chapter 5 immediately after saving the single hostage in front of a very large yellow construction vehicle.

Notes on 3 hidden hostages
#1 - There is 1 hidden hostage on chapter 2. By hidden I mean, you will not get a cut scene or an objective for him and it will not show in the mission summary at the end. He's in a room on the bottom floor where you kick open the door and directly in front of you is an enemy looking at him. he's sitting against a pillar across from the door you come in. You have to go up to him and tap A to save him.

#2 - There is also a hostage on chapter 3, after you rescue the zoo keeper and he opens the gate. There will be 6 guys standing around him. You have to go up to him and hit A to save him but its not an objective.

#3 - And the final hidden hostage is on chapter 4 in the hospital. After you save the first hostage in the hospital, walk back through the door to this room and a guy comes stumbling through a door followed by an enemy. Kill the enemy and press A on the hostage to save him.

Rock, Paper, Scissors

5
Beat your partner at rock, paper, scissors three times in a row
(3)
This can be done easily with a real co-op partner. When not in combat, run up beside him and press . Then use the D-pad to make a selection. When 3 times in a row and it will unlock.
Fancy Meeting You Here

5
Versus: Invite a friend before joining a lobby to play a public match
(30)
From the versus menu press and send an invite to a friend, then join a game once they join. The person who sent the invite gets the achievement.
Job Seeker

10
Versus: In public matches, kill a player with the primary or secondary weapon from every weapon kit
(3)
Just get one kill with the primary weapon (or secondary) from every kit. A kill is 5 points. 4 points for downing him and 1 point for finishing him off.
DIY PMC

10
Versus: Create a custom facemask online (www.armyoftwo.com) and wear it in a public match
(17)
You have to register and have your gamertag linked to your account to be able to upload the mask to the game.

If your having problems see THIS POST.
Death Dealer

10
Versus: Kill 10 players with headshots on a single map in a public match
(7)
For a kill to count as a headshot their head must pop off. You will also see an icon with a head inside a circle beside your name after each "headshot". So just look for this icon each time. Headshots with Assualt Rifles don't take the enemies head off. The Pump Action Shotgun, Desert Eagle, or either sniper work good for this achievement. Also, I found Warzone to be the easiest to get 10 headshots, you have more time and people are focused on the objectives.
Power Couple

15
Versus: Earn the highest partnership score in a Co-op Deathmatch, Control or Warzone public match
(1)
This is easiest on Co-op Deathmatch. Just win the match and you will be the highest scoring partnership. In order to win you will need to have the highest score. Revives, killing the same person and downing another partnership add huge bonuses to your score will help you win.
Future Visions

30
Unlock all Potential Futures
(11)
To unlock this achievement you need to:
- Play through making all negative morality decisions
- Play through making all positive morality decisions
- After completing your positive morality playthrough, you can reload the final chapter from the main menu and pick the oppisite character. You can check the status of this in the main menu under "Extras" and then "Co-op Choices". The spoiler tag has details about the final decision.
You will need to make the decision to kill the bad guy when you playthrough your negative morality playthrough. Then on your positive playthrough have Rios kill Salem, and have Salem kill Rios.
All Guns Blazing

30
Versus: Kill a player with every weapon, including special weapons, in public matches
(5)
You have to get a KILL with both the primary and secondary weapon from each kit AND also a grenade kill. A KILL is 5 points, a DOWN is worth 4, and if you finish him after after a DOWN you get 1 more point. Make sure you finish him off or it will NOT count.

There are 2 special weapons, a RPG and grenade launcher. They are found laying around in each map. If your unsure were they are, ready up before everyone else and you can explore the map until the game starts.

I recommend picking a kit, and sticking with it until you are sure you have the kills you need. Then move down to the next kit and do the same thing until the achievement unlocks.
Bound For Life

30
Versus: In a public match, survive an Extraction map without suffering a single death on your team
(2)
This is easiest to do it from rounds 1-4, but the other rounds are definitely possible. If this doesn't unlock right away keep playing, it may unlock at the end of the next map. Read the tips below.
Survival of the Fittest

50
Versus: Complete all 16 rounds of an Extraction game in a public match
(16)
An Extraction game is played over four different maps and lasts a total of 16 rounds and you will fight an array of enemies which include grunts, heavies, commandos and elites. To gain this achievement you MUST be in the pre-game lobby before the first round starts and you MUST stay in until the end of round 16. This achievement took about 2-4 hours for me and two others to complete.

Tips:
- Find a good position and stay there. If you try running and gunning you won’t last very long as you are seriously outnumbered and overpowered.
- When running low on ammo go up to one of your partners and perform a partner reload. These are infinite and will restock your ammo and grenades.
- Balance your weapon sets. Don’t have four players with a sniper rifle, it just won’t work. I found the best load out is have two players with assault rifles/machine guns, have one player with a shotgun set and just have one player with a sniper kit.
- When heavy enemies appear split up. If you bunch up they will destroy you in no time at all and shooting them in the back is very effective. So spread out and also give him a few headshots. Grenades are also very good if you can throw them accurately.
Big Game Hunting

5
Versus: Kill both members of a single partnership during a public match
(3)
A partnership is two players that joined the game together. Kill both of them and this will unlock right away.
Fresh Meat

5
Versus: Revive your partner and perform a partner reload during the same public match
(2)
Hold when your partner is down to revive them. Hold when standing behind your partner to perform a partner reload.
Scavenger

15
Build a gun using 3 homebrew parts
(1)
The following weapon parts all count as a "homebrew" parts.

Homebrew Stocks
- Rusty Stock
Homebrew Front Mounts
- Metal Plate
- Pipe Launcher 40MM
Homebrew Suppressors
- Screwdriver
- Kitchen Knife
- Soda Can Silencer
Once you have found at least one of these from each category, go into the weapons customization menu by holding down Y and hitting down on the D-pad. Select an assault rifle and equip one from each of the lists above. This achievement will unlock right away.
Heartless

20
Make only negative choices
(3)
Throughout the game you are given morality choices where you have to choose to do either good or bad. To unlock this achievement you need to make only negative choices. Once you have made the decision you should see a small pop-up on right side of the screen saying '- Morality', if it does not say this then quickly reload the last checkpoint. The choices you must make to earn this achievement are as follows:

Chapter 1 - Kill JB?
Yes – Negative Morality

Chapter 2 – Steal Guns and Ammo
Yes – Negative Morality

Chapter 3 – Kill the White Tiger?
Yes – Negative Morality

Chapter 4 – Send Child to get rifle?
Yes – Negative Morality

Chapter 5 – Kill Brezhnev?
No – Negative Morality

Chapter 7 – Risk Shanghai or shoot partner?
Shoot terrorist – Negative Morality
Purist

20
Make only positive choices

Throughout the game you are given morality choices where you have to choose to do either good or bad. To unlock this achievement you need to make only positive choices. Once you have made the decision you should see a small pop-up on right side of the screen saying '+ Morality', if it does not say this then quickly reload the last checkpoint. The choices you must make to earn this achievement are as follows:

Chapter 1 - Kill JB?
No – Positive Morality

Chapter 2 – Steal Guns and Ammo
No – Positive Morality

Chapter 3 – Kill the White Tiger?
No – Positive Morality

Chapter 4 – Send Child to get rifle?
No – Positive Morality

Chapter 5 – Kill Brezhnev?
Yes – Positive Morality

Chapter 7 – Risk Shanghai or shoot partner?
Shoot Partner – Positive Morality
King of the Hill

30
Versus: Win a public match on every map in Co-op Deathmatch, Control and Warzone
(18)
There are six maps total. Win one match on each map in the 3 game types and this will unlock. If the host leaves or you join in the middle of a match it does NOT count.
- Zoo
- Consulate
- Vertigo
- Temple
- Crossroads
- Aftermath

There are 8 achievements with a total of 250 points

Men of the people

25
Escort all hostages to safety.
(8)
There are a total of eight hostages and they are all found in Chapter 9. You will know when you come to the hostages as there will be a short cut scene of them being surrounded by FDI troopers.

The first six hostages have to saved in the conventional way, but when you meet the last two all you need to do is shoot some wooden support beams. Shortly after when you unlock the door with your partner the achievement will unlock.

See the Humanist achievement for hostage rescuing strategies.
Pick a new face

15
There are some bad ass masks lying around the city. Find one or two to change your look.
(4)
The new masks are found in the armored PMC boxes that are guarded by FDI troopers. There are two places to get this achievement. The first place is shortly into Chapter 8. You will come across a PMC box and kill the guards before they can close it. When you search the box (Press ), you will find a mask and the achievement will unlock. You must be playing as Elliot Salem to search this box.

The second PMC box is encountered towards the end of Chapter 9. It is found when you rescue the final two hostages and you can be either Salem or Rios this time.
Hit & Miss

50
Complete Chapter 8 on any difficulty level.
(5)
This is story related and cannot be missed. This is unlocked at the end of Chapter 8. When you and your partner stand next to the final door and are prompted to press to end the chapter. This can be achieved in single player or multiplayer and either offline or online and can be completed on any difficulty.
Train wrecked

50
Complete Chapter 9 on any difficulty level.
(3)
This is story related and cannot be missed. This is unlocked at the end of Chapter 9. When you and your partner stand next to the final door and are prompted to press to end the chapter. This can be achieved in single player or multiplayer and either offline or online and can be completed on any difficulty.
Paging Dr Wu

35
Dr. Wu is digging up some intel for you. Make sure he stays alive long enough to find it.
(3)
This is story related and cannot be missed. You meet Dr. Wu again in Chapter 8 where he assists you in your escape. He cannot die so you don't need to worry about being an expert marksman to keep him alive. This achievement unlocks pretty late, it unlocked in the loading screen for me, well after I finished helping him.
Good Guys

25
Meilin Jun betrayed the civilian resistance but if it's of no consequence to you, let her live.
(1)
You meet Meilin Jun in Chapter 9 and you are faced with the decision of killing her or letting her live. To get the achievements for saving her and killing her quickly you can make any decision. Once the achievement unlocks, pause the game and reload last checkpoint. Then watch the short cut scene again and pick the opposite decision before proceeding with the game.
Good fellas

25
Meilin Jun is a snitch and a traitor. Give her what she deserves.
(1)
See Good Guys for more information.
Can it really be that simple?

25
You've got a chance to take out Jonah, the leader of the FDI. Don't blow it.
(2)
This is earned in Chapter 8. You find Jonah carelessly pacing around in a room with huge windows whilst you squat nearby with your trusty sniper rifle. To unlock this you must kill him with a headshot, as the achievement picture suggests. If you re playing co-op both players will gain this achievement.