I assume CC BY-SA satisfies the conditions for this jam?
Hmm, maybe? The effect of that licence seems to be to prevent the person building on the game from selling it exclusively - since anyone who buys it is then entitled to distribute it for free.
I guess it's ok on the grounds that (a) people share RPG PDFs all the time anyway, and people can generally be trusted to pay for them; and (b) if anyone finds it off-putting they can always choose not to use this particular seed.
My understanding was wrong, haha.
ShareAlike — If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.