(Heavy spoilers) What clue/log do you think was the hardest to figure out?

This should be a tough one!

Now most of the ship logs usually points one clue to the next one, but as we all know, not all the clues are as simple as walking to a place and updating your ship log. Some are much fainter and require you to theorise your next move.

Now, I'll swallow my pride: I did NOT go through the entire game completely blind on my first playthrough. There were some parts of the game where I felt so stuck I couldn't help myself but to throw the towel in the ring and look up some parts, and i think we've all done that.

As for the log i consider the hardest to achieve, I honestly think that the Ash Twin Project was the hardest. I know its the last log you're suppose to achieve, but to be blunt, I wasn't even ashamed of myself for looking up how to get it, since i found the clues to be far too faint for me to ever have figured it out on my own.