Genesis 6 button controller

I got the 6 button contoller from Sega for the Genesis but haven't come across a game that supports it. What were they made for? Also what is the "Mode" button on the controller used for?
This is a guess, the Street Fighter II games for the Genesis?

As for the mode, a toggle between 3 button mode and 6 button mode? Also a guess...:)
Lots and lots of games supported the six button. Mostly fighting games... I know Comix Zone supports it :)

And yes, the mode button has a purpose... if you hold it down while turning the machine on, the six button functions like a normal three button. This was necessary for some games, Ristar comes to mind. It would randomly lock up if you used a six button on it.
I think it might have been unofficially supported... If I remember correctly, the MK manual and box mentioned nothing about 6-button support. Was the pad even available when the game came out?
yeah, it was. I bought MK when it came out in USA, together with a 6 button pad which had just been released too.
I liked the button layout of those games-X, A, Z, C for attacks, Y or B for block (and a run button in MK3). It was rather intuitive. Too bad the ports of those games really suck. :)
Shadow Squadron [32X], SamSho [Genny & SCD], and Fatal Fury Special [SCD] support the big6 as well.

Popful Mail is an SCD game that don't like it much - many random graphical glitches.
Streets Of Rage 3 also supports 6 buttons, let you do their finshing combo moves stright off (like Axel double kick) and back attacks which normaly have to be a different way (Holding B button for a while then letting go *e.g Axel Double Kick*, or pressing B, C buttons at once *Back attack*)