For me it was Dead Space 2 when I was 12-ish. For reference, at this point the most gruesome/gorey/violent media I was exposed to was the Halo 3 Flood levels and the original 2 Alien movies.
I had way too much fun playing it to be traumatized by it at the time, although when i was old enough to understand the horror of the whole "your memories and experience becoming food for a god-like being that has absolutely zero respect for your existance", that did inform my perspective of other media such as Evangelion or Childhood's end when I watched them for the 1st time.
What was your equivalent to this? I've heard the Resident Evil games are quite common for this but I want to hear your perspective.
Uff, hard to say, a lot of the ones comented before applied to me.
As old pc gamer still missing one of the most influent scariest games. Alone in the dark… when you have to deal with the monsters added to frustration of bad controls…
Also dark seed, with all those HR Gigger stuff…
This is the one that immediately popped into my mind. “Alone in the Dark” is the game that made me realize I don’t ever want to play another horror game again! :-D