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.
Read every Journal Entry.
100% Completion + 1%.
Collect everything.
Collect every Feather.
Reforge every Legendary Weapon.
Conquer every Fortress.
Collect every Mask.
Catch every Herptile.
Catch every Fish.
View every Lookout Point.
Say the perfect words in every Relationship.
Complete every Side Quest.
Reach Lv 100.
Visit every Fast Travel location.
Light every beacon.
Finish the Completionist Skill Tree.
Unlock every Skill.
Finish the Generalist Skill Tree.
Finish the Main Quest.
Finish the Speed-Runner Skill Tree.