How do you like your probability of success?

[Flatus Maximus]

Does success = the PC surviving the encounter?
Does non-success = the PC dying?
Does success = the PC gaining some big benefit?
Does non-success = the PC losing some big benefit?

Let's say 100% means you cannot fail to succeed in the encounter (achieve the objective, e.g., kill all the baddies), while 0% means you cannot win (you can run away, but TPK if you don't).

So, no, I'm not at all sure that the chances of winning (either real or perceived) makes the thing more or less fun.

Though I believe you, that answer surprises me. (BTW: "Hard-fought" doesn't have to mean "grinding," at least not for me.) I far more enjoy a fight where the outcome is, at least initially, uncertain. To each his own.

 

[keterys]

I tend to prefer a 60-80% chance of success on any given action (ie, hitting with an attack, making a skill check). Enough of a chance of failure there's suspense on the roll, but not so high that you're likely to fail more than, say, four times in a row.

In terms of TPKs, I tend to prefer at least a 99% chance to avoid them.
In terms of a fight the PCs must likely flee from, I'll probably slip a couple %, but I think they're too easily turned into TPKs, so... meh
In terms of a fight in which a PC dies, but they'll otherwise prevail... 90% would be acceptable, though I actually trend higher.
In terms of any encounter whatsoever in which there's a chance their _objective_ is failed - be that rescuing someone in time, obtaining the macguffin, whatever... I'm okay with the 60-80% from before.
In terms of any _adventure_ in which there's a chance they'll fail entirely... 80-100%. I don't want them to fail like total failures cause they've failed three adventures in a row (1 in 9 chances come up pretty often), and I don't want to have to dramatically redesign the plot every couple months. Every year or so, though, sure.