Controller concept development

[Kyzentun]

I actually have a couple friends that put together a pair of 4 button controllers like that in a cabinet and put OITG on it ~4 years ago. It's pretty fun to play on, even though they separated the two sides too much for double to be easy.
It's been extremely popular at Anime Banzai every year, and gets a fair amount of play in the local arcade it's normally in.

Edit: You can't have the same controller work well for two people playing 4 button and one person playing 8 button. If the buttons are close enough for one person to play 8 buttons easily, it's too cramped for two people to facing forward. If the buttons are spaced to allow two people to fit next to each other, the gap in the middle makes one person playing 8 button awkward.