Enter one of the following codes at the "Unlockables" menu to activate the corresponding cheat function:

All weapons - Enter "LockNLoad" as a code to unlock all weapons.
Bonus weapon - Enter "BlowOffSomeSteam" as a code to unlock a gun with a blade attached to the bottom of the barrel that kills in one hit.
Custom characters - Enter "PeoplePerson" as a code to unlock custom characters.
Custom loadout - Enter "LockNLoad" as a code to unlock a custom loadout.
Insane mode - Enter "Revenant" as a code to unlock the Insane difficulty.
Big head mode - Enter "LincolnsTopHat" as a code.

Emblem locations - There are a total of twenty emblems, which can be found at the following locations:

Arrowtree

1. On the ground floor of the buildings in the back of where you fight the first set of enemies.

Boomtown

2. In the mines, on the second floor of the house after you climb up the chain holding a large crate or the series of wooden molding.

3. Once outside, in the single story building near the billboard that is shot down before the second driving sequence.

4. At the back of the domed structures before taking the zip line to the roof near the conveyor belt.

Mesa Dorado

5. After dismounting the bike at the end of the first driving sequence, inside the building to the left before climbing onto the plateau with the artillery.

6. After the second driving sequence, on the ground floor of the tall building to the left when overlooking the next area from the top of the canal wall.

7. Once in the interior, on the ground floor of the building after the ladder beside the waterwheel and before the rope bridge.

8. To the right of where you start the turret fight with Selena.

9. Once outside again, on the second floor of the building on the right, inside the cavern after the gondola.

Convoy Chase

10. Halfway through the driving sequence, after dropping the totem segment onto the bridge, located behind the totem pole to the left after driving up the newly made ramp.

11. Once outside, near the back side of the area with the square pools and four lantern holding statues (after the spiral staircase and before the gondola).

12. During the fight with Dayden, on the second floor of the building in the middle of this area.

Terra Verte

13. To the left of the statue before entering the city gates.

14. On the way to the top of the governor's mansion, inside the floor where the metal stairs begin. Go to the left of the building near the windows.

15. In the glass building opposite the Waterworks building.

16. Once inside the Waterworks building, on the ground level opposite the entrance to this building.

PSI Complex

17. At the end of the driving sequence, to the right of the elevator.

18. After walking up the conveyor belt, on the second floor of the building to the left after the ladder.

19. Once inside the base of Prescott's tower, behind the elevator.

20. After exiting the elevator into the fight with Prescott's, inside the smaller building to the right.

Hidden multiplayer map weapons

Boiler Room: An Arrow rifle can be found in the bottom middle on the boiler.
Broken Home: A Revenant gun is located on the middle bridge.
Cathedral: A Revenant gun and grenades are at the bottom middle of the map.
Cave In: Check around the platforms in the middle of the map to find an Arrow rifle.
PSI Topside: There are sniper rifles hidden around the map.
Shaft: Battle to the bottom of the map to obtain an Arrow rifle.
Shaman: Look around the center totem; there is something hidden in the tall grass.
Town Hall: The bridge below the roof gap has a Revenant gun.

Trophies - Successfully complete one of the following tasks to get a trophy:

Arrowtree - Casual (Bronze): Complete Arrowtree on Casual.
Arrowtree - Hardcore (Silver): Complete Arrowtree on Hardcore.
Arrowtree - Insane (Gold): Complete Arrowtree on Insane.
Boomtown - Casual (Bronze): Complete Boomtown on Casual.
Boomtown - Hardcore (Silver): Complete Boomtown on Hardcore.
Boomtown - Insane (Gold): Complete Boomtown on Insane.
Double Time (Bronze): Complete any chapter after Arrowtree in Co-op on any difficulty
Dumb Luck (Bronze): Kill 5 enemies at once with explosive damage.
Emblematic (Gold): Collected 20 Emblems.
Finders Keepers (Silver): Collect 10 Emblems.
Found It! (Bronze): Collect 1 Emblem.
Free Style Walker (Bronze): Chain together any 3 physical abilities in 5 seconds or less.
Master Of All (Platinum): Unlock all Damnation Trophies to unlock this Platinum Trophy.
Mesa Dorado - Casual (Bronze): Complete Mesa Dorado on Casual.
Mesa Dorado - Hardcore (Silver): Complete Mesa Dorado on Hardcore.
Mesa Dorado - Insane (Gold): Complete Mesa Dorado on Insane.
Peacemaker (Gold): Complete the Game on Hardcore.
Pedestrian Crossing (Bronze): Kill 20 enemies with a vehicle.
People Skills (Silver): Complete the game in Co-op on any difficulty.
Pyro (Bronze): Kill 20 enemies with explosive damage.
Revenant (Gold): Complete the Game on Insane.
Skeet Shooter (Bronze): Shoot 25 Trip Mines out of the air.
Sniper (Bronze): Get 20 Headshots.
Terra Verte - Casual (Bronze): Complete Terra Verte on Casual.
Terra Verte - Hardcore (Silver): Complete Terra Verte on Hardcore.
Terra Verte - Insane (Gold): Complete Terra Verte on Insane.
Trooper (Silver): Complete the Game on Casual.
Wall Jumper (Bronze): Successfully wall-jump 100 times.
Where'd They Come From? (Bronze): Kill 20 enemies without alerting them.