Grr! iPhone developer Tapulous has launched the latest artist spin-off from its Tap Tap Revenge games: Metallica Revenge.The game features branded visuals and tracks including Enter Sandman, One, Master of Puppets and For Whom The Bell Tolls. And for added rawk factor, there are new modes with four and five tap rails, rather than the usual three. This is the iPhone music game equivalent of turning amps up to 11, we think.The game has gone live today, and costs $4.99. It follows previous games created by Tapulous for Coldplay, Weezer, Lady Gaga and Nine Inch Nails.