So I was wondering, the jam starts in about 24 hours. Will a theme be announced ? or is it open ?

I'm asking, because I don't see what is stopping people from starting to work on the day 1 prototype right now.

Thanks in advance.

Nah, they said in the announcement video that it could be anything so long as it was a new project. Pretty sure the 'theme' is that we're passing it along.

ok. So as I said, what is stopping me from starting to work on my prototype right now, and then release it at the end of day 1 ?

I'm not saying that this is what I would do, just trying to understand that's all.

*shrug* Honor? The spirit of the jam? The creation/last modified marks on your program files? The fact that the devs have said games not following the rules will be disqualified? Cheating yourself out of the jam you signed up for?

their videos have said you can use code from older projects so long as it's a new project.

It may be possible to work on the concept by building a prototype, as long as you don't take any assets/blocks of code from the prototype.