Hi, we've solved every puzzle apart from the microscope puzzle before the knives puzzle, however, when wi attempt to access the attic door, I just get the skeletal wagging finger that prevents me from moving forwards. Are there any specific prerequisites i absolutely need to get before that room will allow me to attempt the knives puzzle

Thanks in advance
I have searched though many guides which have told me the microscope puzzle is not necessarily to the completion of the game is this true?

You don't have to solve it by yourself, but the microscope puzzle must be "finished". To do this you have to visit the hint book in the library three times in a row. The last time it will say "The puzzle is solved".

After that you should be able to approach the knife puzzle.

Thanks for this, really. I've been reading many guides and walkthroughs, since I was stuck in the exact same spot as OP. None of them has mentioned that the microscope puzzle actually really needs to be FINISHED, be it by yourself or with the help of the book. Those that had anything in particular to say about it just said it was an optional puzzle.

Now it may just be that I'm too young, too inexperienced in adventure gaming or what ever. But when I read "optional puzzle" or something along those lines I think that it is something extra. Something you can totally just skip, something you don't need to think about anymore if it's too difficult for you (and yes, it was. It. Was. Inferno.)

Well, now I know not to :D