I have a small game that I worked on for a different jam and I think this could be a good opportunity to turn it into something. Wondering if that would be against the rules/spirit of the jam.
Great question!
Here's our thoughts on it: We prefer that you don't, but if you do, please start fresh!
For example, if you made a 48 hour jam game and liked the direction, start from the beginning. Concept again, start a new prototype, and develop it out with a larger scope. Take what worked from the first and make a "sequel" to the original jam project.