I would make a megaman battle network DX for the gamecube.You go around the net and virus bust in 3rd or 1st person view. buttons=
B=shoot
A=use chip
keypad= move
L/R=jackin or out
C stick=move camera
Z=change styles
start=pause/menu screen

I would make a virtual reality game. In which, you are a reploid. And your RPing. Sort-of-like .Hack//SIGN

I think that the D pad is better for menus on the screen and the joy stick is best for moving around.