Hi kaptainviciorious,
We, too, are excited that you are making a game on Spinoff. Though I do not know how explicit the pics will be, if the game shows no nudity and doesn't describe sexual acts, I do not think it will be an issue. If you want to, you can send us some sample images, and I can ask my colleague responsible for the matter.
By the way, below is the Age Rating of the Spinoff app on the App Store. I guess you could refer to it as a guide.
12+
Infrequent/Mild Mature/Suggestive Themes
Infrequent/Mild Horror/Fear Themes
Infrequent/Mild Sexual Content and Nudity
Infrequent/Mild Cartoon or Fantasy Violence
Please let us know if you have any questions or need more detailed answers. You can reach us at hello@playspinoff.com as well.
Thank you!