It may not be in the general rules, but cmon, it's common snese that a game for a game jam must be made freshly, if not then what's even the point of a time limit.
And also, its called "The perfect jam for beginners." People who have not ever entered a jam/game competition before might not know that, and the premade games rule isn't a rule in all jams, so it should be written in the rules.
