It was proposed somewhere that the winter contest be the one with a restriction of some kind and the summer contest without. I think this is good because it encourages creativity while at the same time giving a venue to present other games that wouldn't fit a restriction.
Product restrictions seem ok but if we restrict to games that use Martian Coasters, where do we draw the line? Would a game that is played on a 6x6 board be allowed in? This has to be well defined and implemented as to not confuse people entering and/or judging.
I myself would love to see more boardless, realtime games such as Icehouse and Icetowers...