Ok /tg/ so my adventurers are trying to escape Hell. It's a typical medieval style D&D format. Any suggestions for things to include would be much appreciated. I've also had a few passive aggressive remarks about my games being easy, so any suggestions on how to solve this without super overpowering the villains would be appreciated too.
>without overpowering the villains
No, don't do this. Make the villains incredibly powerful, well over the PCs level. If they die, they're already in hell. They have to use cunning to escape.
Have them run a gauntlet. A series of encounters, varying between just below level appropriate and kinda easy. Then have them encounter your choice of either the bbeg (who should be able to give a weakened party a run for their money) or a giant fuck off demon. I would also suggest running the low level enemies akin to Tuckers Kobolds and maybe even forcing the party into a confined space, perhaps to escape an encounter they can't win. Remember, its a big world, not everything is gonna be at their level
For some reason, I've always based Hell off the Underworld of Wraith: The Oblivion. Vast, barren emptiness, all kinds of creepy imagery, endless bleakness. Not really any focused torment, just being trapped in a world where everything is dead.
Take some cues from OotA. Force them to scavenge for food (not to survive, but to keep their strength up). Give them exhaustion if they dont. But they're in Hell, so whatever they find to eat has a high chance of fucking with them. Make them roll a con or wis save when they eat, with failure resulting in a mid-tier madness. Make the environment have things that will be so disturbing they stack madnesses on them like with OotA's madness tier system. Also, refer to individual demon lords in the back of the OotA book to add additional madness effects for when shit happens in their lairs/domains.
(The book is in the /5eg/ mega folder if you want to reference it.)
Stuff like this--subverting what necessities they normally take for granted--will turn something as simple as a chunk of not-madness-inducing food into an extremely valuable reward that they will have to plan the use of carefully, or just use on the spot for some much-needed temporary relief.
Demogorgon's layer of Abyss is pretty hot.
>scaly servants of Dagon, including vampiric demon manta ray sorcerers
I advice using Guns'n'roses music.
If you are worried about combat being easy, but you don't want to turn it into a wipe, use a steady stream of opponents, ramping up difficulty until your PCs are using resources but still getting beat back, then taper it off after they beat the opponents that represented what you thought a challenge was, but don't let up stream "easy foes" (foes that hit, but not reliably or for terribly much, and fall in 3 hits or so) at them so they can't rest until they quit the battlefield by concentrating on pushing though instead of total elimination, and they push through to the next area. Maybe have the foes come from the direction you want them to go until they beat the hard foes, and then harry them mostly from the sides, rear, and ceiling (some have to come from the front, to give them something to push through).