Yeah, I've thought about that too, and it's definitely something that's worth discussing for next year. Of course you can have multiplayer games, but I think as an entrant you always need to expect that your judges won't be playing with anyone else. In fact, you need to expect that your players won't either.
One of Epic Inferno's biggest barriers for success, I think, was that it has nothing really to draw anyone to try to find another player. It doesn't look very impressive and the gameplay is too complicated (or perhaps just too difficult to understand). Either way, to get anyone (a judge or otherwise) to want to bring over a friend to try multiplayer you need some kind of exciting hook. It's probably a good idea to stick with AI opponents for your 4k entry, then expand to allow co-op.
Yeah I know. Epic Inferno has definitely some flaws that could be easy fixed. However in my case there was no time and if you play against another player it is lotz of fun
But the point is that if there isn't any restriction against multiplayer games and if there is a competitor with a multiplayer-only game, the judges must adopt to the game and play against another player.
To make a multiplayer game with good chances of being in top of this competition is, of course, very hard in any case.