This was a book I read around 1994-1998. It was in my classroom at primary school, but I believe the teacher had brought it in from home (it was kept on the windowsill with other books belonging to the teacher that we could borrow, rather than in the library with the school's own selection of books). I'm not sure how old the book was at the time; possibly older, definitely not brand new (but it might just have been a bit battered by being borrowed by a lot of eight year olds). I'm not sure if it was actually aimed at children or young adults. It was an outsize picture book, from what I can recall presented in a factual style, about aliens, alien planets and so on; I seem to recall a double page spread showing a suburban house with the roof cutaway, and information around the sides pointing to various things that indicated an alien presence (or something similar; my recollection is hazy!). The part I mostly remember it for was a kind of gamebook section. I think that this was spread throughout the rest of the book, comprising several double page spreads. In the first section you are on board a spaceship which has just crashlanded onto an alien planet, and is quickly sinking (into mud, or quicksand?). You have to select which items from the ship to bring with you to use in later sections, but owing to the time constraints from the sinking can only pick a set number of items. I think the next double page spreads it led you to then had you trying to survive on the alien planet, using the items you had salvaged from the ship; with rescue being the ultimate goal. I think there might have been sections like an encyclopaedia of alien life forms and so on.
It's possible I'm getting my memories conflated with other books; I have read books like Usborne's Puzzle Planet (but this book was definitely aimed at older people than that) which are somewhat similar.