aircraft are also involved in the game. In later titles, notably those released after Grand Theft Auto 2, the player is given a more developed storyline in which they are forced to overcome an unfortunate event (e.g., being betrayed and left for dead), which serves as motivation for the character to advance up the criminal ladder and ultimately leads to the triumph of the character by the end of the storyline. The Grand Theft Auto series belongs to a genre of free-roaming role-playing video games called open world games, and grants a large amount of freedom to the player. Traditional action games are structured as a single track series of levels with linear gameplay, but in Grand Theft Auto the player can determine the missions that they want to undertake, and their relationship with various characters are changed based on these choices. Influenced by the earlier game Turbo Esprit, the cities of the games can be roamed freely at any point in the game, and are examples of open world video game environments which offer accessible buildings with minor missions in addition to the main storyline. There are exceptions: missions follow a linear, overarching plot. These missions are required to complete in order to unlock new areas in the game. Grand Theft Auto III and subsequent games have more voice acting and radio stations, which simulate driving to music with disc jockeys, radio personalities, commercials, talk radio, pop music, and American culture. The use of vehicles in an explorable urban environment provides a basic simulation of a working city, complete with pedestrians who generally obey traffic signals. Further details are used to flesh out an open-ended atmosphere that has been used in several other games, such as The Simpsons: Hit & Run, which has less emphasis on crime or violence, and Lego City Undercover, which reverses the roles of police officer and criminal, although the player goes undercover in gangs for a portion of the game. Criminal activities in Grand Theft Auto games do not go unnoticed by the police. As the player engages in these in-game illegal activities, they may gain a "wanted level", represented by a maximum of five or six stars. A small crime, such as running over a non-player character, may create a one star wanted level situation, while shooting an officer may earn more stars. As the number of stars increase, the amount and strength