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

Green Eggs And... (20 points): Complete Chicken Con Carnage.
Taking Out The Trash (20 points): Complete Double Wide Damage.
Tanks For The Cleanup (20 points): Complete Military Mayhem.
Winner Winner Chicken Dinner (20 points): Complete High Roller Blowout.
Coaster Toaster (20 points): Complete Carnival Chaos.
Just-In-Time Tea-Time (20 points): Complete Ringling Village.
Chivalry is Dead (20 points): Complete Camelot Falls.
Tsunami Envy (20 points): Complete Coastal Calamity.
Mix Masta Pounce (20 points): Perform a Stone Stomp that destroys 10 objects.
Adequate Storm (10 points): Complete a Vortex Race with a bronze medal.
Moderate Storm (20 points): Complete a Vortex Race with a silver medal.
Perfect Storm (30 points): Complete a Vortex Race with a gold medal.
Ginormous Slalom (30 points): Miss 20 gates, but still complete the race.
Apt Pupil (20 points): Absorb all 50 Fire Flyers within the last zone of the campground.
Passive Aggressive (30 points): Reveal 15 Fire Flyers at once without grabbing.
Sprite Slaughter House (100 points): Absorb 100 Fire Flyers at once.
Sprite Cowboy (50 points): Absorb 75 Fire Flyers at once.
Sprite Herder (25 points): Absorb 50 Fire Flyers at once.
Played Nice (20 points): Play in a local multiplayer session.
Friends Till An End (30 points): Release an Orb in multiplayer.
The Boss's Boss (30 points): Release an Orb without losing a Wind Warrior during a Totem approach.
Firenado (50 points): Absorb 1300 Fire Flyers.
Old McDonald (5 points): Absorb 50 chickens.
Tornado Without A Cause (40 points): Destroyed 100 things without absorbing any Fire Flyers.
Slacker (20 points): Absorb the minimum number of Fire Flyers in a non-tutorial level (non multiplayer).
Silent But Deadly (40 points): Military Mayhem Zone 1: Absorb 17 scientists before growing 4 times (non multiplayer).
Who Are You Trying To Please? (40 points): Hold at least 20 Fire Flyers before destroying 25 things .
You're A Loose Cannon (5 points): Destroy a cannon.
There's Waldo (5 points): Unlock first bonus material.
Waldo's Daddy (30 points): Unlock all bonus materials.

Additionally, there are five secret achievements:

Godzilla Would be Proud (20 points): Completed Showdown with Omegaton.
Red, White, And Bruised (30 points): Completed all levels in the United States.
God save the Queen! (40 points): Completed all levels in the United Kingdom.
I Think I'm Turning Japanese (50 points): Completed all levels in Japan.
A Bad Plan (50 points): Disrupted the bad man's bad plan.