Flooded – 60gs – Complete all co-op missions
Overachiever – 100gs – Earn all co-op medals at least once
Dynamic Duo – 60gs – Earn all Gold stars in all co-op missions
Extermination – 60gs – Kill 10,000 enemies in co-op
The Company of Strangers – 20gs – Complete a co-op mission with at least 5 different players
Overrun – 20gs – Complete Operation A
Switched On – 20gs – Complete Operation B
Switched Off – 20gs – Complete Operation C
Evacuated – 20gs – Complete Operation D
Terminated – 20gs – Complete Operation E
Escort Service – 10gs – Keep all Wolverines intact in Operation A, Mission 3
Nowhere to Hide – 20gs – Prevent all Jackals from regenerating their shield in Operation B, Mission 3
Never Knew What Hit Them – 20gs – Kill a convoy target with every stationary gun in Operation C, Mission 3
Brute Force – 20gs – Finish the objectives using only the Brute Shot, melee and grenades in Operation D, Mission 1
Foot Soldier – 20gs – Finish the objective without using any vehicles/turrets in Operation E, Mission 4
Recruit – 10gs – Earn a star of any type in an operation mission
Prodigy – 10gs – Earn your first Gold star in an operation mission
117 – 40gs – Earn all Gold stars in all operation missions
Distinguished Service – 30gs – Earn all medals in the game at least once
Weapon of Choice – 10gs – Score a kill with every handheld weapon (excluding Rocket Launcher and Spartan Laser)
Powered by MJOLNIR – 20gs – Use every ability at least once (excluding Overshield and Seeker Drone)
Skull Combo – 20gs – Complete any mission with the maximum number of Skulls active
Vidmaster Challenge – 30gs – Complete Operation 5, Mission 1 with the Hollow and Black Eye Skulls active
Extra Credit – 20gs – Complete 75 challenges
Pension Plan – 20gs – Earn 25000 Spartan Points throughout your career
Archeology – 20gs – Complete Operation F
Silvertip – 20gs – Destroy all Mega Turrets with the Grizzly tank in Operation F, Mission 2
Vidmaster Challenge 2.0 – 30gs – Complete Operation F, Mission 4 with the Blind and Thunderstorm Skulls active
The Enemy of my Friend – 100gs – Get a higher individual score than your partner on all co-op missions
Immune – 100gs – Finish a co-op mission without becoming infected