4. Path of Exile

Path of Exile Wizard Gameplay

This free RPG is set in the world of Wraeclast, a penal colony off the Island of Oriath. Path of Exile tasks players with conquering countless dungeons, wildernesses, and monsters. There are multiple classes to choose from but the spellcasting classes in this game are particularly powerful. 

One of this game’s highlights is its famous Passive Skill Tree, which offers players a vast web of 1325 skills through which to upgrade and customize your character.

The legendary skill tree in action.