A way to hide authors notes or additional context that would interrupt the reading experience. It would also be great to hide images in a spoiler box for the reader to open it at the right moment. I would like to integrate achievements into a story of mine but honestly they interrupt important scenes too much. Having a gray button with "Achievement" on it which the reader can either click or ignore to continue reading the spicy story would be great.
If you're doing a game story, a way to accomplish this would be to use a chapter at the beginning the player can click into that sets a variable "achievements" to yes. Then, you can use achievement = true tags as you write throughout the story to make the text hidden or visible depending whether they used that toggle or not. That said it would also be nice to have spoiler tags that can be used even outside of game mode, yes.