From DriveThruRpg entry:
Fellowship is a game for 3-6 players about going on an adventure, in the same vein as Lord of the Rings or Wakfu or Jojo's Bizarre Adventure: Stardust Crusaders. The system is loosely based on the Apocalypse Engine. In Fellowship, one player is the Overlord, a maniacal being who has become a Threat to the World, and everyone else forms a fellowship of heroes to stop them. The focus of Fellowship is on the journey you take and the communities you meet, and saving the day is what you're here to do.
Every single player in Fellowship has a ton of narrative control, taking some of the burden off of the typical game master's job. You are playing as a hero, a champion of your people, and you are the truth in all things related to your people. When you play as the Elf, you decide what the Elves are, what their culture is like, what they value and care about, what their relationship is with the rest of the world. When someone asks about the Elves, all eyes will turn to you for the answer.
One player is the Overlord, the one attempting to destroy this world, and they create a character just like everyone else does. They control the forces of evil and they have a master plan that the fellowship must stop. They play by different rules than the other players, and will do their best to make sure saving the world is an epic journey and a fun challenge for everyone.