The final "puzzle" takes in dozens of different words as correct answers. They are graded on how much close to reality they are and in the end determine whether you can go back.

If you're really struggling and want to experience the ending, here are some of the "correct" answers: "creaking", "cold", "submarine", "technician"

Whole game revolves around  the Kursk disaster - a nuclear submarine that sunk in Barents sea, leaving over 20 people trapped for at least few hours to even days in complete darkness. While it's not named in the game, you don't need to know it's history to actually figure out it's some sort of submarine disaster with all the imagery, sound design and some of the lines.

Interesting Trivia

• The note you find at the end is the actual note written by Kolesnikov (scanned texture, it's contents obviously translated into English).

• It's hard to represent complete darkness that the crew of Kursk experienced, hence the fog defying black elements and the final room.

• Being stuck at the bottom of the sea without any power means it gets cold REALLY fast. It's hard to convey the feeling of cold, hence the trudging through snow - which when in "memory zones" turns into air bubbles you'd see while underwater.

• The hidden note that you can find in the large "bunker" contains lyrics to absolutely magnificent "The Kursk" by Matt Elliot. Highly recommend you check it out.

  
  
  

• Kholod 141 was a little hint towards K-141, the actual call sign of Kursk, Kholod meaning "Cold" in Russian. This is some very obscure knowledge so if anyone caught that before playing, let me know :)

My take on the theme was - Death is an opportunity to gain knowledge. You can talk only to the people that are dead at the time of these events, the survivors in the 9th compartment are only represented by the note they left. Another way you could look at it is - each player death (fail state) gives you opportunity to ask 2 more questions.

https://www.murman.ru/kurskmem/crewe.htm
https://the-norwegian.com/2000-2002-kursk-rescue-and-salvage/
https://www.klgd.ru/press/news/detail.php?ID=120381&print=Y
https://www.kaliningrad.kp.ru/daily/24538/718310/