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