your entry's page doesn't require any graphics, though i'd strongly recommend having them (it just makes people more likely to look at it). at the least we'd like to see some kind of description of what the project IS on the page, otherwise it kind of just looks like a spam entry. any level of polish for the actual viewable project is fine though, use your best judgement.
regarding nsfw themes, from the rules section: "Stories can have dark and NSFW themes, but please indicate their existence on your page in some way. That said, the jam runners reserve the right to remove any games with unmarked or offensive content at their own discretion."
TLDR; you can kinda do whatever you want, just be considerate of people potentially downloading your project.
