Here is the full list of all 21 Portal: Revolution achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Reach the surface... again
Solve Chamber 6-6 the boring way
Find a new companion
Reach the Spire
Fling in an endless loop in Chamber 4-11
Get the ball in 4-10 to land perfectly in the socket
Upgrade your portal gun
Find the elevator to the surface
Become an Aperture employee
Thank you for volunteering!
Complete the Chamber 4-9 without knocking over any turrets
Blow up a test chamber sign
Take a shower under one of the gel cleansing fields
Deplete the conveyors' supply of Weighted Storage Cubes
Stare at Conly's mannequins for a really long time
Smear your dirty fingers over Aperture's beautiful glass
Destroy the spire
Deplete the gel supply in Chamber 4-11
Solve the Chamber 6-2 twice
Complete Chamber 5-1 without destroying any turrets
Solve Chamber 6-6 the fun way