I enjoyed the story. I always like the trope of a savior taking another's place, as well as the desperate, guilt-ridden search fueled by regret. Also managed to make it to the end without having to open up the source code : )
One thing for me personally that was a bit difficult to handle was the loud scream sound effect's volume in contrast to the quieter music. I've become extremely prone to panic attacks after recent health issues, and my biggest trigger is unexpected loud sounds. In my case, it causes seizure-like symptoms, and can cause bouts of tremors and slurred speech, sometimes lasting for a few days.
I usually play with my volume cut down to prevent episodes, so I had it adjusted where I could hear the music. When the scream sound effect happened, I threw my phone in the air and had to quickly mute it until I could turn down the sound effect volume preferences. My heart was still pounding half an hour later!
Given the genre, I should have thought to do it once I realized the nature of the story, so it was my fault completely. I would suggest a loud sound warning at the beginning of the game in case players need to adjust the sound effects volume. I understand the scare aspect of it being intentional, and agree the loud scream should be kept as the default for most players. Just consider a small heads up at the beginning for people with sonophobia or similar issues.
Sorry for the long-winded explanation, and please don't think I didn't enjoy your story as a result! Also, please don't take this as criticism, just a friendly suggestion.