Full list of all 20 Open World Game: the Open World Game achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
100% Completion + 1%.
Read every Journal Entry.
Reforge every Legendary Weapon.
Collect everything.
Collect every Mask.
Say the perfect words in every Relationship.
Catch every Herptile.
Collect every Feather.
Catch every Fish.
Complete every Side Quest.
View every Lookout Point.
Visit every Fast Travel location.
Conquer every Fortress.
Light every beacon.
Reach Lv 100.
Finish the Main Quest.
Unlock every Skill.
Finish the Speed-Runner Skill Tree.
Finish the Generalist Skill Tree.
Finish the Completionist Skill Tree.