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