Infinite Ammo, Infinite Grenades and Double Health Regeneration become available options when you complete the game on any difficulty setting.

Complete the following tasks to get the corresponding GamerScore.

Swirly Time! - GamerScore 5:
On any difficulty setting drown a German in a toilet in the Tower of London.

First Time for Everything - GamerScore 5:
Complete a Multiplayer game.

Next Time Take the Stairs - GamerScore 5:
During a Multiplayer game fall to your death.

TV Repairs - GamerScore 5:
On any difficulty setting smash an enemy's head through a TV in the White House.

Reservation for One - GamerScore 5:
On Normal or higher difficulty setting make your way down to Hotal Langteau.

Gravity is a Harsh Mistress - GamerScore 5:
On any difficulty setting toss a paratrooper onto the streets below New York.

Combat Experience - GamerScore 10:
On any difficulty setting Kill 50 enemies in the campaign.

One in the Chamber - GamerScore 10:
In a ranked match Kill a player with the last bullet in a pistol clip.

Sharpshooter - GamerScore 10:
On any difficulty setting kill ALL the paratroopers as you make your way down the skyscraper.

Environmentalism - GamerScore 15:
On any difficulty setting complete 40 environmental or grapple kills.

World Tour - GamerScore 15:
Complete a Multiplayer game on every map in every mode.

MVP - GamerScore 15:
In Team Deathmatch mode win an 8-player ranked or player match with the highest score.

PWNT - GamerScore 15:
In Deathmatch mode complete an 8-player ranked or player match with the highest number of kills.

I Saved the General - GamerScore 20:
On Normal or higher difficulty setting rescue General Donnelly from the D.C. Courthouse.

Need a Ride? - GamerScore 20:
On Normal or Higher difficulty setting meet up with the rescue team in Washington, D.C.

Dolly Madison Award - GamerScore 20:
On Normal or higher difficulty setting save the Constitution from being burned.

Exploding Monkey - GamerScore 20:
On any difficulty setting Kill at least 4 enemies with one explosion.

Defender - GamerScore 20:
On Normal or higher difficulty setting help defend the barricade in New York.

Killer - GamerScore 20:
In any mode get 100 ranked match kills.

Clingy - GamerScore 25:
On any difficulty setting kill 15 enemies in a row by grappling them.

Combat Veteran - GamerScore 25:
On any difficulty setting Kill 250 enemies in the campaign.

Save Yourself - GamerScore 25:
On any difficulty setting escape from New York.

Team Player - GamerScore 25:
In Team Deathmatch mode win 20 ranked matches.

Turning Point - GamerScore 25:
On any difficulty setting complete the campaign.

Uberdork - GamerScore 25:
In Deathmatch mode win 5 ranked matches.

Stayin' Alive - GamerScore 25:
In Deathmatch mode without dying complete a ranked match.

Run! - GamerScore 25:
On any difficulty setting sprint for a total of 30 minutes throughout the campaign.

Stowaway - GamerScore 30:
On Normal or higher difficulty setting sneak onto the Zeppelin.

Going Nuclear - GamerScore 30:
On Normal or higher difficulty setting rewire an Atom Bomb.

Impeached - GamerScore 30:
On any difficulty setting oust the false President from office.

Killer Instinct - GamerScore 30:
In any mode get 500 ranked match kills.

Oh, the Humanity! - GamerScore 30:
On any difficulty setting destroy ALL the assault blimps at the Tower Bridge.

David and Goliath - GamerScore 30:
Win a ranked match against someone 100 or more leaderboard ranks above you.

Master Sniper - GamerScore 35:
On any difficulty setting Kill 10 enemies in a row with a headshot.

Presidential Medal for Merit - GamerScore 35:
On Normal difficulty setting complete the campaign.

Maybe I Should Go Outside... - GamerScore 40:
In any mode get 2,500 ranked match kills.

One Man Army - GamerScore 45:
On any difficulty setting Kill 400 enemies in the campaign.

Dead-Eye - GamerScore 50:
On Normal or higher difficulty setting complete any mission with an accuracy of 80% or higher.

Presidential Citizens Medal - GamerScore 75:
On Hard difficulty setting complete the campaign.

Presidential Medal of Freedom - GamerScore 100:
On Insane difficulty setting complete the game.