An old-fashioned walkthrough (in written form, not any playthrough videos) written by me can be found here:

http://adventuredoor.net/walkthroughs/subject-13-walkthrough/

It is a complete walkthrough, in fact I dare say it is the most complete walkthrough for Subject 13 in written form (at least that I have seen) with many screenshots, including a guide to find all the testimonies.

Thank you. Have not used it yet, but thank you for putting it all together.