Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

A Mess of Stiff Staff Sergeants (15 points): Kill Inferno's Sergeants in single player.
Airborne (10 points): Pilot a helicopter in single player.
From Cold Dead Hands (15 points): Steal all Inferno's Weapon Crates in single player.
Goody Two Shoes (15 points): Bring 20 Prisoners to the Church in single player.
Inferno's Briefs (15 points): Steal all the Document Briefs in single player.
Jonesing for Relics (15 points): Return all the Relics to the Museum in single player.
Lord Master of Great Skill (30 points): Get "Skill Level - Alien" in single player.
Mega Kill Combo (20 points): Get a 50x Damage Streak in single player.
Supply Problems (15 points): Destroy all Mining Carts in the Kaabe Mountains in single player.
The Daily Grind (20 points): Get a character to max level in single player.
To Hell and Back (10 points): Complete Mission 9 on any Difficulty in single player.
Tough Stuff (20 points): Complete all missions on Hardcore difficulty.

The following achievements require the "Coldstrike Campaign Pack" bonus downloadable content:

Extraction (10 points): Mission 1 - Rescue all the civilians in single player.
Intelligence (10 points): Mission 2 - Acquire all intel on Coldstrike’s plans in single player.
Pansy Worm (30 points): Mission 3 - Defeat the Panzer Wyrm.