as in if all the in game content was streamlined and put into one story, how many books would it be?
(lets assume all busts and images also count as a page or two as well. our main character tries every single scene, transformative and completes every quest.)
I don't know any answer to this, but even supposing I knew the paragraph/word count in total, there'd still be some extra questions. Like, how many lines could fit onto a page? Or characters, words, paragraphs, etc. Graphics and options make how many lines there are in a single scene in TiTS vary, so it's kind of weird to think of. Characters and words all very in terms of width, so a line of just "I I I" repeated over and over would have a much higher word count than "Preferably preferably preferably" as a single line.
Of course, that's predicated on the concept of the book length being based on the number of pages, which itself would, of course, vary based on both line count, line length, paragraph count, how many lines could fit into one page, etc. There's also the possibility of it being counted based on word count. Your post, mentioning "all busts and images also count as a page or two as well," implies that the book length would be based on page count, not word count, but if looking at it from word count, that still varies a lot. You mention trying every scene, transformative, and quest, but the thing is that plenty of scenes have variations, often minor but occasionally major, for a variety of differences, and not to mention one-off scenes where you can't go through all the variations. Hell, there's scenes which can not exist in the same playthrough, as far as I know. Even if we got a total wordcount of every scene in the game, or a total line count and image count, we would need to either weed out mutually contradictory scenes and even words that depend on parsers, or just not really curate it.
And then there's still the question of how much fits into a book. How many words, or how many pages, are there per book? Is it 6 words, like Hemmingway's shortest "novel"? Is it 1.1 million words? Is it 100 pages, 1000, 10000? I don't know the wordcount or linecount of TiTS, but if I did, I'd still need to know these stipulations to answer. It would, in fact, be entirely possible to put everything into one single book, if you really wanted to.