While the concept of players being engaged by police had been a feature of most entries in the series since the first Need for Speed title, the development of Most Wanted saw the gameplay mechanic enhanced and firmly introduced into the series through the employment of a complex system. When players become engaged in a police pursuit, usually from conducting a traffic offence (referred to as "Infractions" in the game) in sight of a police unit (such as speeding), their aim at this point is to escape from the pursuit by either evading or taking out pursuing vehicles. The game's on-screen HUD is modified during a pursuit, including highlighting pursuing police units on the mini-map, displaying the vehicle's heat level, and adding a Pursuit bar at the bottom detailing the number of police units in the pursuit, how many have been evaded, and how many have been taken out. The pursuit system calculates how the police handle the player via the heat level accumulated against the player's current car. Heat accumulates from committing offences and continually evading capture by the police, with higher levels of heat causing the police to be more aggressive, from employing additional tactics and tools (such as roadblocks, spike strips, and police helicopters), to involving stronger, faster police cars such as police SUVs and Federal units. If a player has only one car actively pursuing them, reinforcements may be called in and arrive after a period of time.
Multiplayer in Most Wanted consists of online modes, which were available for the Xbox 360, Xbox, PC and PlayStation Portable editions of the game. Up to 4 players can participate in an online race and can race in 4 game modes including circuit, sprint, lap knockout and speed trap. Furthermore, there is the option to enable Performance Matching in an online race - all cars in the race are automatically upgraded to match the performance (i.e. top speed, handling, etc.) of the fastest car in that particular race. As soon as the race is over, all modifications made to the cars by performance matching are removed. The online multiplayer lobby was shut down on August 1, 2011, though it is still possible to play the game in multiplayer, but through an unofficial modification called "Most Wanted Online". 2b1af7f3a8