itch.io

For future reference, it is possible to reuse code.

It's possible! Previous jams had participants who developed their submissions for the Virtual Boy, the Sega Dreamcast's VMU, or even their own engine.

Here is our form for submissions past the deadline!

https://forms.gle/HSbSbEUneihSJMNh6

Please bear in mind that this link is open for a week.

As long as it isn't sexually explicit or too graphic, it should be good. Think "what could I show that won't have ESRB rate it AO+?", or something like that. Since it's crudely-drawn for artistic purposes, this is okay.

Visceral environments (e.g. those with themes similar to Guts World from Yume Nikki or Visceral World from .flow) are fair game, if that's what you mean.

From past jams, we do have a few YNFGs based on existing media, so it is indeed possible.
The usual jam rules do apply, of course.
If the source material does have any written policies or guidelines on derivative works however, do take them into consideration.