The way I see it, your players should be afraid of dying every time a fight kicks off while knowing you'll take care of them if they do in fact die.
You do this by being ruthless when they overstep (don't pick fights with dragons) but then not just ending their story on a death.
How about D&D games? There's a lot of discussion of TPKs but you see, my dream is for games to be fun. Part of that fun is, of course, to have them seem like they take place in a real world. This means that TPKs should be possible. But TPKs are not, for obvious reasons, always fun.
Frankly TPKs are "safer" to pull off in Call of Cthulhu than D&D or RuneQuest. Making a new character in CoC is a lot faster, easier, (and less painful) than D&D. Killing off a 9th level rogue is a disaster. The player has to start all over again and work your way up.
For this reason, while I am still fully willing to kill off fantasy player characters, I am slightly slower to pull the trigger just randomly. I might think up a reason for them to get a bonus on their save against lightning roll. Or I might have the Big Bad give them The Choice: "Give up all your wealth and magic items and swear an oath to leave my lands never to return, or I'll kill two of your party members." PLAYERS: "Which two?" BIG BAD: "It's a surprise." There are lots of tricks and tips I can use. And you can too.
What's the worst TPK you ever had as a GM or player? How did you recover?
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