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

Mutant (10 points): Shoot five mutants in one game.
One Wave (10 points): Make it to the second wave without losing any humans.
Cooperation (10 points): Get a score of 15,000 during an Xbox Live Co-Op game.
Competitive (15 points): Win 30 Xbox Live versus games.
Nice Catch (15 points): Rescue a human with a mid-air catch.
Getting Better (15 points): Make it to the third wave.
Fifteen Grand (15 points): Get a personal score of 15,000.
Run! (20 points): Survive the first 75 seconds without shooting, bombing, or teleporting.
Baiter Bane (20 points): During an Xbox Live Co-op game, kill five baiters in any level without using any smart bombs.
Five Waves (20 points): Make it to the fifth wave.
Twenty-Five Grand (25 points): Obtain a personal score of 25,000.
Protect All Humans (25 points): Lose no humans in the first three waves.