Yeah, I agree. This is something that I tend to do as well. I mean, you're writing for a specific audience who has presumably already played the game so already has the necessary background that you don't really need to cover. This can lead to bad habits though when you go back to original writing - you have to remember to turn that part back on, lol. But I think it's a good idea to do with fanfiction.

I cheat a lot too since this is a game where there are a lot of different possibilities. I think it's sort of important, when you're writing a one shot especially, to flag the reader pretty quickly what scenario you're in. Tossing in the warden's last name in the first paragraph, leaving hints about what past choices have been made in the narrative as you go along is pretty important. So it's sort of a different challenge.