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.
Collect every Feather.
Collect everything.
Collect every Mask.
Reforge every Legendary Weapon.
Light every beacon.
Say the perfect words in every Relationship.
Complete every Side Quest.
View every Lookout Point.
Catch every Fish.
Catch every Herptile.
Reach Lv 100.
Conquer every Fortress.
Visit every Fast Travel location.
Finish the Speed-Runner Skill Tree.
Unlock every Skill.
Finish the Generalist Skill Tree.
Finish the Main Quest.
Finish the Completionist Skill Tree.