We would probably ask that you use your discretion in a matter like this. If you don't intend to unscreen your app, then don't worry about including spoilers in it — we mods don't mind it. If you'd planned to put spoilery material in a post or a thread, we would as you to put it behind cut text (in a post) or warn for/ask the player's opinion on spoilers in the subject line (in a thread). If you're accepted, we would also recommend you put up an OOC permissions post for including spoilers, to forego the asking-in-a-thread part. It's up to you when spoiler-material is no longer a spoiler, as we cannot really judge something like that.

If you wanted to post your app to your own journal, you may want to change both the text and background to white so that people can highlight it to read if they want to, like so: {Like so!} If you like that idea, you can do that with this:

{<span style="color:white; background-color:white;">Spoilers go right in here!</span>}