The original concept of Atomic Heart began in the late 2000s. Originally, it was meant to be a movie, and many CGI renders of concept footage can be found on the internet. While many production studios loved the idea, none of them agreed to make the movie. This led to the creation of the game instead.
Mundfish, the creators of Atomic Heart, created a game before Atomic Heart, which not many know about. The game was called "Soviet Lunapark" and was a VR co-op action shooter. The game received mixed reception, but was quickly shut down so Atomic Heart could be created. Many assets of Soviet Lunapark can be found in Atomic Heart, such as the enemy designs.
The track "PT-1X12" by Geoffrey Day(GeoffPlaysGuitar) is a reference to Peter Tchaikovsky's "1812 Overture",both melodically and namewise.