If a theme can throw your planning, then my take is you’re doing too much ‘planning’. Anyways, if you look at the past winners, they tend to be projects that obviously adhere to the theme, seem to be produced in a single weekend, and don’t feature marketplace or other purchased content. There might be exceptions; just going off of what I’ve noticed.
It’s looking like there might 150+ entries to the thing (!!!), so even if a particular game is in the top bracket, it’s still unlikely to catch one of the top three spot. I say, just relax and enjoy the ride. Don’t stress over it.