Barring in mind the rules, can a GDD still be made to lay out the foundation for the game as long as the doesn't begin until the jam starts?
I don't see any issues with coming up with plans. As long as actual creation of the game in a development program isn't happening.
That's actually really great to know! I've wanted to make a submission since Preggojam#3, But I didn't know if planning out a concept on paper throughout the year and then developing a game with those ideas during the submission period was allowed.
Yeah, I think making a GDD is fine, but only if you don't prep artwork beforehand - that'd be too much, if you ask me.