Go for the Gold
Win a gold metal on a challenge map.
Out of the Blue
Once you have control of both portals, only enter the orange portal.
Find all the Rat Man dens.
Is Anyone There?
Complete the game without ever taking a bullet.
Saw That One Coming
Cause a rocket sentry to destroy its own rocket when the rocket has been redirected back towards it.
The Camera Adds 10 Pounds
Knock a turret over with a security camera.
Like a Rat
Trap yourself in a test chamber so that GLaDOS has to help you continue.
A Feeling Like Floating
Dissolve a turret.
Tests Like Chicken
Find the chicken's test results.
Beat 5 advanced chambers
Beat 10 advanced chambers
Vanilla Crazy Cake
Beat all advanced chambers