Here is the full list of all 10 Dear Esther: Landmark Edition achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Finish Chapter 'The Beacon'
Finish Chapter 'The Caves'
Finish Chapter 'The Buoy'
Finish Chapter 'The Lighthouse'
Drown Once
Die from falling off a cliff once
Uncover 4 urns
Trigger all director's commentary
Trigger all voice over points
Walk 5000 steps