I’ve never played in a game in which I was scared. 90% of the time, I’m the GM. So I’ll make my answer about a game that I ran which my players explained was the scariest for them.
The system was the second edition of Warhammer Fantasy Roleplay. The characters were hired to enter a Sanitorium and defeat some mysterious figure called the “Sun Prince” who had taken over the place and turned all of the inmates into crazed zealots.
The atmosphere took big cues from Silent Hill. Everything was rotting, dark, partially living (“breathing” walls, bleeding steps, giant eyes and orifices here and there). The further the heroes went the more crazed it became.
My goal was to slowly dial up the insanity and terror as they descended into the building. The villain was in the basement (had the players entered the Sanitorium via the ground floor or sewers, the villain would have been on the top floor). I explained to the players that their characters constantly felt feverish and sweaty; and that the air tasted like salt and rust. One of the key monsters (a crazy weird horror out of Hellraiser) smelled like Vanilla. Another quadruped monster-child smelled like cinnamon.
It was a huge success and the players were honestly creeped out. A success!
The game system lends itself well to gritty, creepy horror because of its built-in sanity and corruption mechanics. If I ever ran WFRP again, I’d probably use Lamentations of the Flame Princess instead (and tack on the corruption/insanity mechanics).
29th – Most memorable encounter
30th – Rarest RPG Owned
31st – Favourite RPG of all time