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The purpose of a game jam is that you make a game during the jam. In this case it's pretty obvious that you made most (if not all) of it before the jam even started.

If you are looking to promote your current project, then how about creating a stand-alone spinoff of it for this jam? If you don't want to invest all that effort on just a game jam submission, then remember that you can still use any of the assets created for your jam game in your main project later.

As hopelessly mentioned before:  The purpose of a game jam is that you make a game during the jam.
If you would like to follow their recommendation, you can make a submission for a spinoff game with that in mind. I will update the verbiage to make it more concise!