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.
Expedition to the Barrier Peaks
"Expedition to the Barrier Peaks" was first played at the Origins II convention in 1976, where it was used to introduce "Dungeons & Dragons" players to the science fiction game "Metamorphosis Alpha". In 1980, TSR published the adventure, updated for first edition "Advanced Dungeons & Dragons" rules. The adventure was not updated for later rules systems, but a Wizards.com article did provide a conversion to "Future Tech". It included a separate booklet of illustrations, in both color and black and white. The adventure is an old-time favorite of many "Dungeons & Dragons" fans, including Stephen Colbert. It was ranked the fifth-best "Dungeons & Dragons" adventure of all time by "Dungeon" magazine in 2004, and received positive reviews from "White Dwarf" and "The Space Gamer" magazines. The other adventures in the "S" series include S1 "Tomb of Horrors", S2 "White Plume Mountain", and S4 "The Lost Caverns of Tsojcanth".