Win a gold medal on a challenge map.
Beat 5 advanced chambers
Beat 10 advanced chambers
Beat all advanced chambers
Once you have control of both portals, only enter the orange portal.
Find all the Rat Man dens.
Complete the game without ever taking a bullet.
Cause a rocket sentry to destroy its own rocket when the rocket has been redirected back towards it.
Knock a turret over with a security camera.
Trap yourself in a test chamber so that GLaDOS has to help you continue.
Dissolve a turret.
Find the chicken's test results.
