The biggest obstacle standing in the way of a successful handheld version of Rock Band is the controller. Guitar Hero DS solved this problem by including a peripheral that plugged into the extra GBA slot. The touch-screen was used for strumming with a special pick that also came bundled with the game. The PSP, with no tough screen and limited peripheral attachment options, seems like it could be at a disadvantage here. Harmonix have solved this problem by tweaking the gameplay to rely entirely on the four face buttons.