Open-world games still enforce many restrictions in the game environment, either because of absolute technical limitations or in-game limitations imposed by a game's linearity.
Players typically do not encounter loading screens common in linear level designs when moving about the game world, with the open-world game using strategic storage and memory techniques to load the game world in a dynamic and seamless manner. Games with open or free-roaming worlds typically lack level structures like walls and locked doors, or the invisible walls in more open areas that prevent the player from venturing beyond them only at the bounds of an open-world game will players be limited by geographic features like vast oceans or impassable mountains. While games have used open-world designs since the 1980s, the implementation in Grand Theft Auto III (2001) set a standard that has been used since. In video games, an open world is a game mechanic of using a virtual world that the player can explore and approach objectives freely, as opposed to a world with more linear and structured gameplay.
