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

Long Live Chief Berni-ni (5 points): Revive the Fire Chief, Berni-ni.
A Shocking Development (10 points): Use the Harvest Chief, Diggi-dodo's power on a Booli.
Sober the Stinkers (15 points): Get the stinkers off slugs.
Abracadabra, Alakazam! (20 points): Transform a Booli using the Animal Chief, Ali-mali.
Flotsam and Jetsam (25 points): Completely flood a level using the Swimmer Chief, Fini-ni.
The Way the Booli Crumbles (30 points): Shatter a Booli into pieces using the Stone Chief, Te-tera.
Dibs on the Drumstick (35 points): Make a feast for the flappers.
And Stay Out! (10 points): Kick the Boolis out of Ooga.
Taste Tester (5 points): Swallow 15 unique items.
Death Defier (5 points): Complete 22 levels without dying.
Bone Collection (35 points): Collect all of the bones of the Ancient One.
Join the Revolt (5 points): Complete a split screen cooperative level.

The following achievements require "The Forgotten Chapters" bonus downloadable content:

Comrade Crate (15 points): Open the crate to discover the contents. You monster.
Super Spear Hero (15 points): Kill the baddest tuska in all the land.
The New Boss (20 points): Get the Glow Stone.