By that I mean, can the game have a bit of visual novel elements and a bit of other genre if it plays into the story?
"visual novel" genre definition is rather vague and ultimately it is up to the reader to decide what they consider a visual novel. for the purpose of the jam, as long as the part which is the visual novel style text progression feels like the most significant portion of the game, it still counts as a visual novel despite having hybrid elements from other genres.
Word. I mean, most people would call the Zero Escape games "visual novels," even though they have a bunch of very puzzly and gamey puzzles in them. Speaking to the vague nature of the label, interestingly enough (to me personally, at least ... I just find this particular case really fascinating), there are too many people that disparage Persona 3 Portable for being "just" a visual novel - despite the fact that it has exactly the same core gameplay loop as every other version of the game, the exact same story, the exact same level of interactivity and choice, the exact same Tartarus grind, and at least double the amount of content, even when compared to the recent remake. And those same folks rarely call Persona 5 or the aforementioned remake "just visual novels," even though, ultimately, they are like 80% visual novel mechanics with 20% of dungeon crawling sort of ... attached.
Genre labels in games, and by "gamers," are a trip sometimes. But I digress.