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.
Discovered the secrets of the Resistance
Discovered the realms' defiance
Assisted in solving the riddles
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
Invite a friend to play We Were Here Forever!
Escaped from the deep dungeons
Survived the trials
Solved the riddles
Entered the Royal Cemetery
Unlocked the catacombs
Assisted in unlocking the treasure vault
Unlocked the treasure vault
Assisted in discovering hidden treasures
Discovered hidden treasures
Obtained the lens of the Astrolabe
Entered the Ruins of Rockbury
Realigned the light beam
Assisted in discovering Rockbury's secret
Discovered Rockbury's secret
Obtained the rete of the Astrolabe
Entered the Sunken Mines
Assisted in navigating the sunken mines
Navigated the sunken mines
Refueled the Nautilus
Assisted in negotiations with the guardian
Negotiated with the guardian
Reforged the base of the Astrolabe
Obtained the base of the Astrolabe
Unlocked the Bell Tower
Restored the device
Paid the ultimate price
Escaped.. but at what cost?
Escaped from Castle Rock