Open world
There is no consensus on what the earliest open world game is, due to differing definitions of how large or open a world needs to be. Ars Technica traces the concept back to the free-roaming exploration of 1976 text adventure game "Colossal Cave Adventure", which inspired the free-roaming exploration of "Adventure" (1980), but notes that it wasn't until 1984 that what "we now know as open-world gaming" took on a "definite shape" with 1984 space simulator "Elite", considered a pioneer of the open world; Gamasutra argues that its open-ended sandbox style is rooted in flight simulators, such as SubLOGIC's "Flight Simulator" (1979/1980), noting most flight sims "offer a 'free flight' mode that allows players to simply pilot the aircraft and explore the virtual world". Others trace the concept back to 1981 CRPG "", which had a free-roaming overworld map inspired by tabletop RPG "Dungeons & Dragons". The overworld maps of the first five "Ultima" games, released up to 1988, lacked a single, unified scale, with towns and other places represented as icons; this style was adopted by the first three "Dragon Quest" games, released from 1986 to 1988 in Japan.
LucasArts adventure games
LucasArts' first adventure game was the 1986 title "". The game's development was led by David Fox, with contributions from Douglas Adams, Christopher Cerf, Noah Falstein and Brenda Laurel. Based on the film of the same name, it is LucasArts' first video game adaptation of a film. It is the only adventure game not published by LucasArts, as "Labyrinth" was published and distributed by Activision. "Labyrinth" differs significantly from later LucasArts adventure games as it uses text parser gameplay as the main means of play.
"Labyrinth" was followed in 1987 by "Maniac Mansion". "Maniac Mansion" was the creation of Ron Gilbert and Gary Winnick, and marked the debut of SCUMM, the game engine that powered all but two of LucasArts later adventure games. The game was also the first LucasArts adventure game to be released for DOS. "Maniac Mansion" was LucasArts' first full graphic adventure game, using a point-and-click interface rather than the text-based gameplay seen in "Labyrinth". A menu of verbs allows the player to choose how to interact with the game's environment. "Maniac Mansion" aims to parody the horror genre. The game was subject to several enhancements and re-releases, and was included as a game within a game in its sequel, "Day of the Tentacle".