Do you have an old game or project you wanted to finish but never did, well now's your chance! dig up that old project to from the grave and work a bit more on it, then submit it for others to see and play.
The theme of the jam is finishing an old project of yours, but what if you don't have an unfinished project, well then you can use the back up theme: Zombies.
Keep the game Safe-For-Work (Blood and gore are allowed with trigger warnings).
Trigger warnings if there's anything to graphical or swears and things like that.
If you're finishing a project of yours you don't need to make it Halloween themed, but if you're making a new game you do have to follow the back up theme of Zombies.
While you are allowed to have the code you had when you left the project, make sure at least 95% of the new code was made during the jam.