This was at a small convention some years ago (between 3 and 6, I would say), in the middle of nowhere, Finland. The game master and the other players were all strangers to me. There was maybe three or four players. I went in to fill the table, anyways, as I did with Savage worlds in the same con, too.
The game was Cthulhun kutsu (a translation of what the name implies) or Call of Cthulhu, I don't remember anymore and I don't know if the edition was even named. We were of the coast guard (maybe somewhere in USA?) and there was a ship that did not react and might be just floating, not steered. We are to figure out what is happening.
Knowing that there are many ways to play Cthulhu, I asked the game master if we (as players) should be trying to complete the mission, first and foremost, or if we should be playing up all the horrors and how real people would react when facing such. The latter was the answer, but not said with confidence. This was what I guessed, since the Finnish rpg scene has been very partial to character immersion and such matters, presumably due to the connection to the Nordic larp scene with similar emphasis.
We went to the ship, communications died, the ship seemed empty, we poked around a bit, saw a human figure, there came tentacles that hit someone who failed rolls and was obviously (to the players, not the characters) infected by them. My character failed their sanity roll and there was a random roll of insanity; I get something to the effect of delusions or paranoia or combination thereof, so gleefully started playing that my character saw the others as faceless humanoid tentacle monsters, too. I escaped to a life boat, tried to hide there, kicked the others and threatened them with a flare.
The game master seems a bit frustrated over the course of events and has my character fall unconscious by fiat as some kind of beam hits her head. As befits the situation, I don't remember much about the rest of the game. It ends with the characters in a life boat, with some tentacles rising from the sea. We thank the game master. There is some after-play talk and the game master says something to the effect of having hoped that we could defeat the thing. Well, that is precisely what I asked at the very beginning, now wasn't it? The game was okay by my standards, anyway, but the game master felt a bit disappointed.