I beat 999 and got the knife ending, which naturally left me unsatisfied. I do like the ability to skip through seen text in further playthroughs, though it would be nicer to be able to skip puzzles as well. It seems as though to get all the endings you will have to go through most of the puzzles twice and some even three times. I may take a break after this second go around so that I don't get too annoyed with that. I found a handy flowchart online that shows what doors I have to go through to get each ending so that will help minimize repetition.