Which is the most difficult adventure you remember Gming? Pick one where the players were freaked out, or completely lost, or in a strong moral conundrum, or absolutely terrified... why do you think the players reacted that way? Which elements made the adventure that strong?
The most difficult scene I can remember was from an old one shot one on one horror adventure with Rosie. It involved her char on a Jach Heausteau like diving expedition, coming across a sunken german U boat, and after entry from a busted bottom portion she along with some her friends emerged into the dry musky interior and to save oxygen took off their scuba helmets.
Given the nazi's had all comitted suicide rather than suffocate down here I decided to be "nice" and let them have enough air to explore some. Describing that abandonded musky tomb at the bottom of the alantic with powdered dust and a aura of eveil was challenging yet devilshy enjoyable.
I had her char jumping at everything by the end of it, to the point of having fired her spear gun into a corpse that sagged and fell out of a char after she passed it.
The real kicker was after she returned to the expidition boat on the surface. What she didn't realize was all the mumified bodies and sealed in area had given rise to the classic version of "king tuts curse" a fungus infeciton found in the egyptian burial tombs which causes extreme halliucinations and probable death for the infected victims (a half dozen divers in this case)
And so after an incubation period, the research boat slowly degenerated into what she was positive was a WWII ship, with undead Nazi's coming to claim her for violating their resting place.
In reality she was butchering the entire crew, (not that she knew this of course) one of which was her chars fiancee, the doc who had pieced together enough of the situation to realise what was wrong with her, tried to talk her out of it, but was killed because to her char he was a "vile german-speaking nazi butcher"
After a time the disease ran it's course (with her the only survivor) and she woke up on the ship all alone in the middle of the atlantic surrounded by corpses, pieces of corpses, and a mostly ruined and slowly sinking ship transformed into a total slaughter house.
Then end scene, was when she got to the cabin, found the ships security cameras, and was able to see (and hear from her fiancee's yelled pleas as she bludogened him to death with a co2 tank) the exact manner and reason for the crews unfortunate demise..
The whole thing was devilishly hard to orchestrate correctly, but the final ending when her char realized what she'd done was the perfect twist that made it well worth the effort.