@jrpohlman39 good news... I had the exact same problem a while ago with Robotron. Please see the discussion here: You can map this in mame menu. Within the game it can be accessed via keyboard by pressing TAB key. You can map player 2 joystick to player 1 inputs. Even better: with the new and very cool mame2003-plus-libretro emulator there is a core option implemented for this. Once set, it enables this control scheme for all dual joystick games. See this github issue 278 and github issue 216 There is a dedicated thread in this forum for mame2003-plus here