boost. During the career mode, each challenge features a final boss, which, once defeated will yield access to their specific mods (mods being upgrades that provide enhanced functionality to a standard powerup e.g. Khan's titanium shield), and customized cars. At the final boss challenge, all the bosses meet together for a final race. A trailer and tips video for the game on Xbox Live mentioned a feature that never made it to the final game. The feature, called "double tap", was meant to allow a player to combine several powerups of the same type for a more powerful effect, by double tapping the special power use button. The video was removed near the release of the game and little, if any, mention of the feature, seems to have been made again. The "double tap" feature was not present in the free multiplayer demo of the game offered on Xbox Live. Multiplayer The game can be played with up to four players in split screen, and can be taken online for a maximum of 20 players over the internet, or over LAN in the PC, Xbox 360, and PlayStation 3 versions. In a custom game, options can be set before each match that determine the layout of power-ups, car classes, number of laps, and the car to race. A match type called "World Tour" is essentially a quick play option for players who want to jump into a match. Here, every player is given a random car and thrown into a random series of courses with a standard ruleset. Multiplayer also offers "Team Racing" mode. Two teams (Alpha & Omega) can put themselves head to head either publicly or private. During races, each player accumulates points for their finishing position. While in team racing, powerups will not affect the player's own team members with the exception of Shock. Players can send a racing challenge to an online friend. If the second player beats the time, they can send the updated challenge back. These challenges go back and forth until one person concedes. Players can also use the Share button, and post their achievements to Twitter and Facebook. Reception The game was very well received overall by critics, with a Metacritic score of 82/100 on the Xbox 360 and an 81/100 on the PlayStation 3 and PC. Sales In the US, Blur sold 31,000 copies in its first five days of release