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.
Entered the Ruins of Rockbury
Navigated the sunken mines
Negotiated with the guardian
Discovered Rockbury's secret
Discovered hidden treasures
Unlocked the treasure vault
Solved the riddles
Survived the trials
Escaped from the deep dungeons
Escaped.. but at what cost?
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Escaped from Castle Rock
Paid the ultimate price
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
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
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