If you do end up making a game for this, I think it would be cool to also keep the basic controls game that you have done already. It would be fun just to use to control R.O.B. , maybe even use it to have him beat up on a NES console a little! One other option, is instead of using two controllers would be to use a Star Raiders controller with an overlay for various movements. I don't know how much more complicated that would make the coding of a game, but it could be a nice touch to make two underutilized game accessories be used in one game.
If you do make this, I may have to modify a R.O.B. to have a bit more wood design incorporated into his body!