I ran a game last night, a pre-written module (the game is not relevant) with a certain difficulty level (not so difficult in my opinion), and the party is composed of moderately experienced players and a newbie. The party had to face some enemies, and seeing that they had problems with previous encounters I decided to tweak the fight a bit to make it easier: removed some opponents, made the enemy reinforcements arrive late so the PC's had a little more breathing time between turns, made other enemies waste time boasting and taunting, removed abilities from the "BBEG" stat block.
It still ended in a TPK.
Mostly because the PC's rolls were just TERRIBLE, rolling so bad they ended in the impossible range of, like, 0.0009% chance of failure. What can a GM do in such a situation? I know this question is kinda connected to this other question, but suppose there is no logical/plausible way to save the party and the players might feel cheated if saved by stretching the rules, the world, the story or whatever else. Do we just accept the thing and move on? Personally, I always thought that a TPK was an ending too, although not a much satisfying one, but the players might beg to differ.
Reworded for brevity:
The PCs fight enemies, there's a TPK because of incredibly bad rolls and no way to save the group without it looking like cheating, not in the system we're using at least. Do I cheat anyway, talk to the group and laugh it off, explain that it can happen and change campaign?
Since someone believes that in certain games you cannot fail or die, let's say that we're talking about Pathfinder 2e.