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.
Complete a certain challenge.
Reach the end.
Activate the Town laser.
Activate the Quarry laser.
Activate the Shady Trees laser.
Activate the Marsh laser.
Activate the Treehouse laser.
Activate the Bunker laser.
Activate the Jungle laser.
Activate the Monastery laser.
Activate the Keep laser.
Activate the Desert Ruin laser.
Activate the Symmetry laser.