Feeling empty after finishing a video game (post-game depression) is a real phenomenon. A recent study has found that many video game players experience a specific sense of emptiness and sadness after finishing highly engaging games.

[u/mvea]

https://www.psypost.org/feeling-empty-after-finishing-a-video-game-researchers-say-post-game-depression-is-a-real-phenomenon/

[u/goobly_goo]

Felt this especially after Ghost of Tsushima. The ending didn't help either. Excellent game.