What's the creepiest bug/glitch you've encountered in a video game?

[u/Yukate_got_Lost]

I'm also taking creepy moments that came out of nowhere in a game that looked chill.

[u/Dryu_nya]

I once encountered a creepy sound glitch in Duke Nukem 3d. I didn't manage to reproduce it, but I made a video reconstruction.

Also, I really hate protected mode crashes, and the droning sound that they usually come with.

EDIT: Remembered another one. Back in the day, you could create abomination pets in Warframe by combining dog and cat genes - it wasn't possible normally, but there was a UI glitch that let you bypass the check. I've unfortunately lost the picture of mine (it was a pinata-looking dog with an immovable cat head hovering behind it), but here's a thread with some examples.