Jeremy Russo, Lead Designer writes:
"Once we got through the prototyping phase and determined the basic hardware, we couldn't just jump right into development and drag and drop Guitar Hero onto the DS. We still had some major gameplay issues to sort out. The iteration on the Guitar Grip that you read about in the previous entry was one of the biggest challenges, but there were others that were equally as important… and some of them are things that players probably wouldn't think much about. The style and placement of the fret highway and player immersion in the world of rock stardom are both issues that you'll hear about later, as well as the debate between a four button and five button peripheral. But I'm here to talk about two mechanics that we felt would make or break the game's success, and both were in real danger of getting removed from the game at one point: Touch screen strumming and Guitar Duels."