Here is the full list of all 39 We Were Here Forever achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Negotiated with the guardian
Navigated the sunken mines
Discovered Rockbury's secret
Discovered hidden treasures
Paid the ultimate price
Unlocked the treasure vault
Solved the riddles
Survived the trials
Escaped from the deep dungeons
Escaped from Castle Rock
Escaped.. but at what cost?
Restored the device
Unlocked the Bell Tower
Obtained the lens of the Astrolabe
Assisted in discovering hidden treasures
Assisted in unlocking the treasure vault
Unlocked the catacombs
Entered the Royal Cemetery
Obtained the rete of the Astrolabe
Assisted in discovering Rockbury's secret
Realigned the light beam
Entered the Ruins of Rockbury
Obtained the base of the Astrolabe
Reforged the base of the Astrolabe
Assisted in negotiations with the guardian
Refueled the Nautilus
Assisted in navigating the sunken mines
Entered the Sunken Mines
Discovered the secrets of the Resistance
Discovered the realms' defiance
Assisted in solving the riddles
Invite a friend to play We Were Here Forever!
Escaped from the keep
Escaped from the Jesters' realm
Escaped from the Jesters' Toybox
Assisted in escaping from the trials
Assisted in escaping from the deep dungeons
Escaped from the chasm
Escaped from the prisons