Why make a game that has been made? Guitar Hero and Rock Band have a common flaw, you cannot create your own songs. What is wrong with the PC versions of the Guitar Hero clones? They are unreliable and hard to use, not to mention the lack of editing capability. Why use the source engine? The source engine a stable and reliable product that can deliver an updated engine and a large user installment. Not to mention, the software developing influence of the installed user base. Source screams "I want a rock rhythm game!!!"

This is not a guitar hero clone, this is evolution. Why pay $5 for a song pack that you probably wont like, when if you own hl2 you can customize your own music with music mod!