The Treehouse of Horror XXIII Event was a Halloween-themed event released on October 12, 2012. It was the first Treehouse of Horror event.
The event contained several new Iimited time Treehouse of Horror characters, decorations, tasks, and buildings. Along with the update came several new standard buildings, decorations, and characters such as Edna Krabappel and Otto Mann. It ended as of November 8, 2012.
The Treehouse of Horror XXIII Event also included a social element - Players could visit their friend's Springfields and vandalize buildings with Toilet Paper and Eggs. When the Player vandalized homes, they would receive one Treat; if a Player cleaned the Toilet Paper or Eggs from a building they could collect a Treat as well.