Full list of all 12 Portal: Still Alive achievements worth 200 gamerscore. It takes around 6-8 hours to unlock all of the achievements on Xbox 360.
Beat all advanced chambers
Beat 10 advanced chambers
Beat 5 advanced chambers
Dissolve a turret.
Knock a turret over with a security camera.
Trap yourself in a test chamber so that GLaDOS has to help you continue.
Win a gold medal on a challenge map.
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.
Find all the Rat Man dens.
Once you have control of both portals, only enter the orange portal.
Find the chicken's test results.