Army of Two: The 40th Day Cheats

Unbreakable (25): You must survive an entire level in one session without being downed on normal difficulty or above
Not So Bad After All (10): You need to tie up 15 enemy combatants instead of executing them
Healer (10): You need to heal your partner 10 times
Co-Op Sniper (10): You need to Co-Op Snipe 5 enemies
Attention Grabber (10): You need to allow your partner to snipe 5 guys while in Mock Surrender
In Synch (10): You need to kill two enemies with simultaneous Quick Draws while in Co-op Mock Surrender
Pumpkin Patch (10): You need to shoot 2 enemies in the head with a single bullet
Total FistBump Destruction (10): You need to finish the game as best friends
Total Fistbump Deflation (10): You need to finish the game in a fractured friendship
The Truth Is Right Here (20): You need to listen to all of the Radio Broadcasts
Loot and Pillage (20): You need to collect $1,000,000
Full Arsenal (30): You need to collect All Weapons and Weapon Parts
Touch Not a Cat but a Glove (50): You need to shoot all Maneki Neko cats in the game
Hate Monger (10): You need to customize a weapon to high aggro
The Optimist (5): You need to make a positive coop morality choice
The Pessimist (5): You need to make a negative coop morality choice
Humanist (30): You need to save every hostage
Secret Achievement (5): Continue playing to unlock this secret achievement
Secret Achievement (5): Continue playing to unlock this secret achievement
Secret Achievement (10): Continue playing to unlock this secret achievement
Secret Achievement (10): Continue playing to unlock this secret achievement
Secret Achievement (10): Continue playing to unlock this secret achievement
Secret Achievement (15): Continue playing to unlock this secret achievement
Secret Achievement (30): Continue playing to unlock this secret achievement
Secret Achievement (30): Continue playing to unlock this secret achievement
Secret Achievement (30): Continue playing to unlock this secret achievement
Secret Achievement (50): Continue playing to unlock this secret achievement
ecret Achievement (5): Continue playing to unlock this secret achievement
Secret Achievement (5): Continue playing to unlock this secret achievement
Secret Achievement (15): Continue playing to unlock this secret achievement
Secret Achievement (20): Continue playing to unlock this secret achievement
Secret Achievement (20): Continue playing to unlock this secret achievement
Secret Achievement (30): Continue playing to unlock this secret achievement

Chapters of Deceit DLC Achievements
Complete each achievement to receive the allotted gamerscore.

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.
Good fellas (25): Meilin Jun is a snitch and a traitor. Give her what she deserves.
Good Guys (25): Meilin Jun betrayed the civilian resistance but if it's of no consequence to you, let her live.
Hit & Miss (50): Complete Chapter 8 on any difficulty level.
Men of the people (25): Escort all hostages to safety.
Paging Dr Wu (35): Dr. Wu is digging up some intel for you. Make sure he stays alive long enough to find it.
Pick a new face (15): There are some bad ass masks lying around the city. Find one or two to change your look.
Train wrecked (50): Complete Chapter 9 on any difficulty level.

Unlockables
Big Heads Cheat Code: Complete the campaign on Casual difficulty
Infinite Ammo Cheat Code: Complete the campaign on Casual difficulty

Unlock additional weapons and items from the first Army of Two
When you first start the game it will check your devices for the first Army of Two game If it finds them you will get additional weapons and mods to use from the beginning (granted you reach the trash container at the start of chapter 1).

Unlock new costumes
Civilian costume: Beating the game on any difficulty
End costume: Beating the game on any difficulty
Mall costume: Beating the game on any difficulty
Medium Armor costume: Beating the game on any difficulty
Old school costume: Beating the game on any difficulty

Beginning Weapons Fullly Upgraded
When you first start the game you are given money to upgrade your weapons. Upgrade your weapons/buy new ones, then continue onwards till the cutscene with the moral choice, make it. Go back to the main menu during the cutscene with the explosions, select campaign, select the one you just did. Click new. You will have all the weapons, upgrades and money from the previous mission, and can upgrade your weapons once more. Repeat till all beginning weapons are upgraded/bought.