I waited until late last night, for the announcement of the theme, and went to sleep pondering "cycles".

The first thing I did was brainstorm (on paper) anything I could think of related to cycles. My list was:
Cycles, Recycle, Birth/Death, Pheonix, History, Bicycle, Seasons, Circle of Life, Time/clock, Majora's Mask, Turn-based ________, Compute cycles, Washing machine, Power turbine, Moon cycle - lycan

Once day/night occured to me as a reasonable thing, I thought of games that use it as a dynamic and how. Minecraft and Terraria were obvious, but then I thought of Castlevania II. And immediately after: what if I reversed roles? I've been a big fan of the series for a long time, so this appealed to me. 

Next I brainstormed different details that might inform my core gameplay loop. My mind was already buzzing with classic Dracula lore, and how I might bring Bram Stoker's original concepts back out, to make something that's a bit of a twist on what people typically think of as vampire strengths/weaknesses (for instance, not being hurt by the sun, but instead losing his powers).
This brainstorm happened on a white board:

As I thought about these things, I also thought of a meta-narrative of cycles of violence, which I want to weave into the story and actually give the player moral choices to make, as opposed to just simply killing everything and powering up for a final battle. I thought it would be interesting if the player had to be more cunning, and even have incentives to not kill humans. I'm still working out how to translate this into the game for sure, but I felt like I had enough to go on and get started. I knew I had a side-scroller concept which was good enough to get rolling with, and that day/night cycles would absolutely play a key component. So I will likely need graveyards or some such similar things where the player can hide during the day, or skip to night. and then the hunger mechanic, which may simply get worked into health. A suggestion from another jammer who has offer to collaborate on character design.

So, I am using Godot for the first time, and after this short brainstorming session, I spent the majority of my day working out the basics. Here's the progress so far: