Grand Theft Auto III is an action-adventure game played from a third-person perspective. Players complete missions—linear scenarios with set objectives—to progress through the story.[4] It is possible to have several missions available at a time, as some missions require players to wait for further instructions or events.[5] Outside of missions, players can freely roam the game's open world, and have the ability to complete optional side missions. Liberty City is composed of three boroughs: Portland, Staunton Island, and Shoreside Vale; the latter two areas become unlocked as the player progresses through the storyline.[6]