Indie game storeFree gamesFun gamesHorror games
Game developmentAssetsComics
SalesBundles
Jobs

Ah - so it's a second joystick that is used for the game.  Now I understand - thank you.  Further research has indicated that the second fire button on the Epyx/Konix 500XJ only works with a Sega Mega Drive and the NES.  So not the C64 sadly :(