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.
Adventure game
The first known graphical adventure game was "Mystery House" (1980), by Sierra On-Line, then at the time known as On-Line Systems. The game featured static vector graphics atop a simple command line interface, building on the text adventure model. Sierra would continue to produce similar games under the title "Hi-Res Adventure". Vector graphics would give way to bitmap graphics which also enabled for simple animations to show the player-character moving in response to typed commands. Here, Sierra's "King's Quest" (1984), though not the first game of its type, is recognized as a commercially successful graphical adventure game, enabling Sierra to expand on more titles. Other examples of early games include Koei's "Night Life" and "Danchi Tsuma no Yuwaku" (1982), "Sherwood Forest" (1982), Yuji Horii's "Portopia Serial Murder Case" (1983), "The Return of Heracles" (which faithfully portrayed Greek mythology) by Stuart Smith (1983), Dale Johnson's "Masquerade" (1983), Antonio Antiochia's "Transylvania" (1982, re-released in 1984), and "Adventure Construction Set" (1985), one of the early hits of Electronic Arts.