Full list of all 13 The Witness achievements worth 1,000 gamerscore. It takes around 15-20 hours to unlock all of the achievements on Xbox One.
Reach the end.
Complete a certain challenge.
Activate the Treehouse laser.
Activate the Quarry laser.
Activate the Jungle laser.
Activate the Town laser.
Activate the Marsh laser.
Activate the Keep laser.
Activate the Bunker laser.
Activate the Monastery laser.
Activate the Shady Trees laser.
Activate the Desert Ruin laser.
Activate the Symmetry laser.