As with previous installments of the Final Fantasy series, Final Fantasy VII consists primarily of three major areas: an overworld map, field maps, and a battle screen. The overworld map is a 3D model, featuring a scaled-down version of the game's fictional world, across which the player travels between the game's locations. As with preceding games in the series, the world map can be traversed by foot, on chocobos and in an airship or sea vessel (in this case, a submarine and a plane used as a boat). It also includes an additional means of transportation—a buggy. On field maps, characters are directed across realistically scaled environments, consisting of 2D pre-rendered backgrounds which represent locations such as towns or forests. Initially, the player is restricted to the city of Midgar, but as the game progresses the entire world becomes accessible. Progression through the game's storyline is largely developed by way of scripted sequences, although pre-rendered cinematic cutscenes are also used.