The first interactive game to feature a boss was dnd, a 1975 role-playing video game for the PLATO system. One of the earliest dungeon crawls, dnd implemented many of the core concepts behind Dungeons & Dragons. The objective of the game is to retrieve an "Orb" from the bottommost dungeon. The orb is kept in a treasure room guarded by a high-level enemy named the Gold Dragon. Only by defeating the Dragon can the player claim the orb, complete the game, and be eligible to appear on the high score list.