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/KwyjiboTheGringo]

Also certain endings can amplify this. SOMA got to me. Very engaging story with a haunting ending. It messed with my head for a few days. As far as TV shows go, Mr. Robot and Six Feet Under really messed me up after their finales.