Complete the following achievements to unlock Xbox Live Gamerscore points.

Carlson's Raiders (10 points): Complete 'Semper Fi' on any difficulty. 
(Solo only) 
Stormed Peleliu (15 points): Establish a beachhead on the island of 
Peleliu on any difficulty. (Solo only) 
The Last Stand (20 points): Survive the land and air conflict surrounding 
Okinawa on any difficulty. (Solo only) 
Stabbed in the Heart (20 points): Complete all missions on the Eastern 
Front on any difficulty setting. (Solo only) 
Get Your Hands Dirty (30 points): Complete 'Semper Fi' on Veteran difficulty. 
(Solo only) 
Saved Private Ryan (10 points): Save the soldier before he burns to death. 
(Solo or co-op) 
Bloody Peleliu (30 points): Complete 'Little Resistance' on Veteran difficulty. 
(Solo only) 
Weapon of Mass Destruction (15 points): Radio in a naval bombardment that 
kills at least 4 Japanese soldiers. (Solo or co-op) 
The Sword Is Broken (30 points): Complete 'Hard Landing' on Veteran difficulty. 
(Solo only) 
No Safe Place (15 points): Burn an enemy out of a tree with the flamethrower 
in 'Hard Landing' (Solo or co-op) 
Architect (30 points): Complete 'Vendetta' on Veteran difficulty. (Solo only) 
The Professional (15 points): Shoot all of Amsel's henchmen, including their 
attack dog, without reloading. (Solo only) 
Gunslinger (15 points): Assassinate General Amsel with a pistol shot. 
(Solo only) 
The Hammer Strikes (30 points): Complete 'Their Land, Their Blood' on Veteran 
difficulty. (Solo only) 
Scorched Earth (30 points): Complete 'Burn'em Out' on Veteran difficulty. 
(Solo only) 
Firestarter (15 points): Complete a mission using only the flamethrower. 
Melee, grenades and explosives are OK. (Solo or co-op) 
Fearless (30 points): Complete 'Relentless' on Veteran difficulty. 
(Solo only) 
Hell on Wheels (30 points): Complete 'Blood and Iron' on Veteran difficulty. 
(Solo only) 
Iron Fist (15 points): Destroy all towers and bunkers in 'Blood and Iron'. 
(Solo or co-op) 
No Return (30 points): Complete 'Ring of Steel' on Veteran difficulty. 
(Solo only) 
Ruthless (15 points): Kill 15 enemies while mounted on a tank in 'Ring of Steel'. 
(Solo or co-op) 
When It Rains, It Pours (30 points): Complete 'Eviction' on Veteran difficulty. 
(Solo only) 
Shot in the Dark (10 points): Kill 10 enemies while the lights are out in 
the subway in 'Eviction'. (Solo or co-op) 
One Bad Gato (30 points): Complete 'Black Cats' on Veteran difficulty. 
(Solo only) 
The Sum of All Zeros (15 points): Down 45 Japanese Zeros in 'Black Cats'. 
(Solo only) 
Lights Out! (10 points): In 'Black Cats', blast out all of the spot lights 
in the Japanese cargo convoy. (Solo only) 
Blowtorch & Corkscrew (30 points): Complete 'Blowtorch & Corkscrew' on 
Veteran difficulty. (Solo only) 
Setting of the Sun (30 points): Complete 'Breaking Point' on Veteran 
difficulty. (Solo only) 
Mortar-dom (10 points): Kill 8 Japanese with thrown mortars in 'Breaking Point'. 
(Solo or co-op) 
Guardian Angel (10 points): In the final battle for Okinawa, save Sergeant 
Roebuck. (Solo or co-op) 
For the Motherland (30 points): Complete 'Heart of the Reich' on Veteran 
difficulty. (Solo only) 
Bearing the Burden (30 points): Complete 'Downfall' on Veteran difficulty. 
(Solo only) 
Rough Economy (15 points): Kill 3 enemies with a single bullet. 
(Solo or co-op) 
Close Shave (10 points): Survive a Banzai attack. (Solo only) 
Snake in the Grass (15 points): Take out a Japanese soldier while he is lying 
in wait in the grass. (Solo or co-op) 
Grave Robber (15 points): Collect all Death Cards in the game. (Solo only) 
Kamikaze (15 points): Complete any level on Regular difficulty or higher 
using only melee and grenades. (Solo only) 
Throw a Six and a Half (15 points): On Hardened or Veteran difficulty, 
complete a level without dying. (Solo only) 
Purple Heart (5 points): When staring into the face of adversity, show 
courage and persevere. 
War Hero (40 points): Complete the game on any difficulty. (Solo only) 
Hardened War Hero (100 points): Complete the game on Hardened or Veteran 
difficulty. (Solo only) 
Get Your Left Foot Wet (30 points): Complete a match in Campaign Co-Op mode 
over Xbox LIVE. (Online co-op only) 
Get Your Right Foot Wet (30 points): Complete a match in Competitive Co-Op 
mode over Xbox LIVE. (Online co-op only) 
Blue Ribbon (25 points): Complete a 4-player Competitive Co-Op match in 1st 
place over Xbox LIVE. (Online co-op only) 

Additionally there are two secret achievements.

Secret achievement (0 points): Unknown. 
Secret achievement (0 points): Unknown.