Game supporting multiple buttons

[matthey]

Flashback
Street Fighter 2
Sqrxz 1 & 2
Hired Guns (supports 3 buttons with mod)
Doom (supports 6 buttons with 6 button controller and mod)
ADescent
Chaos Engine (CD32 version)
Lotus II (CD32 version)

A Sega controller C button is the same as the CD32 blue button (B=CD32 red). There are also an increasing number of WHDLoad, JST and hard drive installable versions of games that support 2 buttons. You might be able to switch wires so C uses the A button and wire up to C (original A).

[matthey]

I still need to get round to making that Megadrive pad adapter... in theory it should be possible to program to use all the buttons if only two wires are swapped round. Not that that will help with existing games, but I hope to be able to take advantage of it in future.

The ADoom manual recommends swapping pins 5 & 7 and putting a 470 ohm resistor between them. Hired Guns and ADoom support 3 buttons then. I recall some emulators did also. None of the buttons map to other CD32 buttons so different code has to be used to read a 3 or 6 button Sega controller than a CD32 controller.