It's pretty straightforward
Earlier this month, Lionhead Studios put the call out for fans to design their own Achievement to be integrated in Fable Anniversary. The results are in, and the winning entry "Are you not entertained!?" will require players to complete all eight rounds of the Arena without taking a break.
So, not exactly the most inventive Achievement out there, but at least one of the runners-up -- "Obtain every melee weapon in the game (excluding Avo's Tear or Sword of Aeons)" -- didn't take the top prize. I can never earn those. The "Farticus" Achievement for passing gas on Whisper in the Crucible before deciding her fate seemed like a lock, but I guess not.
Design an Achievement Winner! [Lionhead]