Very deep systems for a two week jam, impressive!
Starting off with the letter almost seems a little unnecessary when your characters already have so much information to tell, almost felt like it could have been omitted entirely. Really liked the investigative journal mechanics, would have liked to see the 'time' mechanic of it all perhaps used a bit more. It's the first thing we learn but didn't seem to really come up again.
Unfortunately even with the walkthrough I was too stupid to complete the cryptic puzzle, something about the last part of it I could not get right and I got too frustrated. So I had 8/10 witnesses and struggled wayyy too hard on the puzzle till I gave up.
Tiny lil bug: Some of the rooms on the lower deck say 'My pocket watch' at the exits.