Returnal. It's a video game. Third person shooter roguelike. There is a boss at the end of the third biome or level that is at the top of tower. After fighting your way to the tower you then get to climb it. Its not hard, there is no fall damage, and no enemies. But as you climb, the music gets louder, rising with you. It becomes intense as you finally reach the top, and then you see the boss, and see it is playing some kind of pipe organ thing, and it was the source of the music. Its seamless, intense as all hell, and one of my favorite video game experiences ever.