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.
Sonic Adventure
Prior to the release of "Sonic Adventure", most 3D platform games focused on exploration and collecting items; "Sonic Adventure" changed this with its linear gameplay. According to "GamesRadar", it was one of the first sixth-generation console games and changed the industry "forever", despite its glitches. "Joystiq" wrote that both "Adventure" and the original "Sonic the Hedgehog" had innovated through effective linear level design and by feeling "good to play". In 2009, "GamePro" listed "Sonic Adventure" as the seventh-best platform game of all time, saying it had not aged well in certain aspects but its core gameplay remained among the best of the "Sonic" series. Several journalists ranked the game among the series' best, but "Kotaku" argued the addition of voice acting and greater focus on plot changed Sonic into "a flat, lifeless husk of a character, who spits out slogans and generally has only one personality mode, the radical attitude dude, the sad recycled image of vague '90s cultural concept".