The digital Dungeon Master

Have you ever played a role-playing game (RPG) such as Dungeons & Dragons? In a pen-and-paper RPG, one of the players takes the role of the storyteller or Dungeon Master (DM). The DM keeps track of the score and describes the scene in words. The DM controls all non-player characters (NPCs), enemies as well as extras. The DM is also the referee who interprets rules.

In a computer game, the listen-update-render loop takes the role of the Dungeon Master. Instead of players moving pieces on the table, Java input listeners trigger game actions. Instead of players rolling dice and looking up rules, the update loop manages game mechanics. Instead of the DM deciding on random encounters, the update loop controls NPC behavior. Instead of the DM describing the scene in words, the renderer draws the scene in 3D.