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