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