And further, as said earlier, a "save or die" that isn't really a "die" isn't much of a problem apparently
Yeah it removes them from that fight, but not for long.
The durations are usually very short
1d4 rounds in the case of Cause Fear, 1/casterlevel in the case of Scare, and both have a HD limit of no higher than 5HD per creature (and limit how many creatures are affected).
There are other fear effects out there, but they seem to follow the same power level
You can be shaken, or frightened, or panicked, or cowering, but no two at the same time.
So, fear effects making you flee a fight are relatively rare and are pretty limited and weak, especially since you'll have big boosts to will saves against fear and even immunity to fear later, provided you know that fear effects are coming and can prepare
My problem is that I don't think fear effects adequately represent a PC's "mental strain".
I feel that a PC should have a representation of mental strain and stress which over time results in the character being worn down mentally just like they can get worn down physically. Either way, once you're worn down too much you'll need to return to town to rest.
I also feel like the Heal skill is extremely weak both thematically and mechanically, for similar reasons, but I only mention that as context. I want a game which is a bit more gritty in terms of recognizing the bodily limitations of a character.
Am I allowed to link a youtube link in chat?
Anyway, without digging to much into the details, I wrote up a form of mental strain where every time something happens which is significantly stressful you check whether your stress is at a breaking point.
Essentially similar to having an anxiety attack.
If you become too stressed, you take on either the shaken, frightened, or panicked condition (although it's not as a "fear effect"), and if needed you flee the current situation. Bringing your stress back down is pretty easy, but it can be slow if you didn't prepare for it, and once you've run out of your reserves of ways to bring your stress down you'll want to return to town to rest and recover.
My bigger problem is, how will it affect the party dynamic when anyone could get so stressed that they take penalties and even flee.
Let's assume that "this change is fun" because it's part of the appeal of the game to be more gritty. The question of whether it's fun being answered, how would the players change their behavior? Would it become just another thing the players prepare for? How would in-fight behavior change?
Would players change their tactics so that the PCs approaching a breaking point move off and switch to ranged weapons?
As I have it now, You get little bit more stressed every time you: fail a save, lose hit points, take nonlethal damage, fail an important skill check, gain a fear effect, an opponent successfully intimidates you, or you interact with your character's predetermined stressors (if any).