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