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

Moby Dick (10 points): Single Player: Destroy the Mecha Orca.
Hot-wired (10 points): Single Player: Capture all 3 hijackable vehicles at least once.
Pyromaniac (10 points): Single Player: Burn 50% of infantry in any Zone: Medium or Hard difficulty in one session.
Ice Cold (10 points): Single Player: Freeze 50% of infantry in any Zone: Medium or Hard difficulty in one session.
Assault Flags (10 points): Single Player: Collect all of the Flags scattered throughout the game.
Fearless (20 points): Single Player: Complete 3 sequential areas on foot: Medium or Hard difficulty in one session.
Wonder twins (20 points): Zone Battle: Use all 4 Co-Op attacks, kill 10 units with each: Medium or Hard in one session.
Zoned Out (20 points): Zone Battle: Complete 6 Zones, each with the help of a different Xbox Live enabled friend.
Escapist (20 points): Zone Battle: Defeat all spaceships in Areas 29 & 30: Medium or Hard difficulty in one session.
Smoothie Heroes (20 points): Co-op Campaign: Kill 100 infantry, one player freezes & the other shatters, on Hard in one session.
Underground Hunters (20 points): Co-Op Campaign: Finish all underground areas with the help of a friend: Medium or Hard difficulty.
Heroes Campaign (30 points): Co-Op Campaign: Complete all areas on Hard difficulty with the help of a friend.