Here is the full list of all 35 Cliffhanger: Challenger of Tomorrow achievements.
Restore the world’s knowledge of Atlantis
Kill Renfrew
Protect free speech
Recruit Jacob ben David
Meet with Hassan-i Sabbah
Beard HPB in her lair
Recruit Ali Murtaza
Find le Spectre
Recruit Doctor Devi Naryan
Drive in the Grand Prix
Overthrow the Four Empires
Recruit Hedy Kiesler
Kill Hitler
Escape Franklin’s Isle
Beat Charles Lindbergh’s transatlantic record
Make a fortune gambling at Monte Carlo
Party with Noël Coward, the Aga Khan, and Wallis Simpson
Survive a walk through the Garden of Forking Paths
Recruit 44
Recruit Princess Sonia
Recruit Liou Hann
Recruit Le Chat Noir
Track Arnold Rothstein down
Face off against the Golden Bat
Overthrow Colonel Klaw
Forge an alliance between Communists and monarchists
Find out the truth about Arkaris’s art collection
Learn the truth about Ah Ken
Permanently acquire Project Colossus
Harness the power of dreams
Decisively defeat the Doomsday Legion
Conquer the criminal underworld
Take down the Syndicate
Ensure the future of scientific progress
Become rich