Divinity Original Sin - Official Guide
In short, this is a party-based, classless RPG that features turn-based combat and a highly interactive world where players are free to do as they please. It supports drop-in/drop-out multiplayer and a unique cooperative dialogue system that lets you, or you and a friend, deeply role-play two characters.
Originally published in June 2014, Divinity: Original Sin was lauded as a modern twist on classic RPGs and lauded by both fans and critics. The Enhanced Edition adds quests, story, gameplay, skills, balance, and new features to the original.