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