Take into account that contest rules state that the game must run on a real 464 without (hardware) expansions. ¿Only 2 players then?
The word "expansions" makes me think of things like more memory or a harddisk or HxC or MegaFlash etc.
A simple 2-player cable doesn't fall into the "expansion" category to me. If you categorize a 2-player cable as an "expansion" then a joystick must also have to fall into this category... in which case you can't actually play our game at all, because it requires at least 2 players - i.e. one on keyboard + one on joystick, or two on joysticks.
I can understand the MegaPlay being categorized as an expansion though, because it's a more rare piece of hardware withsomewhat advanced components, and it (kinda) gives the CPC new inputs it wasn't born with.
But a 2-player cable (and joysticks for that matter) should fall into the standard accessories category in a game-development contest in my opinion.
I guess we'll have to wait and see what the judges say, but I'll definitely be disappointed if they complain about needing a 2-player cable in order to be 3 players.