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