Pro tip. NPC want to live too offers more alternative to combats, make the one happening more interesting.
The Borg games have a whole morale rules to let the NPC flee, but this can be managed based on what makes sense story wise
One of the most amusing and at times frustrating games I ever played was a campaign inspired by the Napoleonic Wars. The French were Gnomes who were extremely bad French stereotypes armed with muskets and liable to flee if their unit got attacked by three volleys OR their officer and/or standard bearer got sniped. Several parlays included awful french accents on the part of the DM and more than one encounter outright avoided by the PCs hiring a bunch of whores to distract or appease the frognomes, complete their objective and move on.
Reminds me of the smartest Batman goon.
I would expect the enemies to be extremely cowardly given that they live in a universe where hell exists.
In a high level campaign I ran, I took the design philosophy that the villains were supernatural (e.g, dragon or lich), the average npc was weak (level 3 or less), and the characters were once-in-a-1000-years heros (level 10-20).
Every now and then they would have an obstacle involving regular humanoids or the local government and they had the option of just steamrolling everything (even whole platoons). It provided a great contrast to the magic-boss death matches and let the characters really feel special.
It also drove home that they were the only ones who could save the day.
I’m generally not big on that approach. But then again, I rarely play at levels where the PCs can really take that superhero approach. Could be interesting to roll with that some time.
DMed a game where an otyugh dragged a PC into it’s trash pit. Bit of a Death Star trash compactor scenario. But he got out and the party beat the otyugh within an inch of its life before it retreated.
When the party passed by the same pit, I described one the otyugh’s eyestalks sticking out before it Noped back under.