Hello! For some reason your posts were tagged as spam.
But let’s go through your questions.
First of all, thanks for the comment, I'm sure there are more people with the same questions.
A game jam is simply a game related gathering. It roots in the music jams where musicians gathered together to play and improvised without the burden of "making a hit".
Answering your questions:
- Yes, anyone can participate
- Yes! We made a free chapter available on top of the demo chapter available in the book page exactly so people who doesn't own the book could join as well. So you can join and use only the free available chapters
- The theme will be revealed as soon as the jam starts! So it’s currently a mystery
I hope this helps! Let me know if there are any other questions.