Ever since the top 101 came out, this particular aspect of RPGs has been on my mind. It's usually the main point of praise for Oblivion, and I've said it myself that it's the best part of Underrail. I didn't elaborate much because I didn't know how to explain the difference between good and bad quest design, but after pondering on it, I've come up with some general guidelines.
- Interact with the game world
If the world should feel like a cohesive whole, the quests should reflect that. They should be parts of it, not isolated, insular pieces of gameplay. A good example of this is the Rattay tourney in KCD: it starts off as more or less a distraction, but when you come to a certain town later in the game, you meet a man whose son was killed after winning, so the tourney becomes an actual event with emotional stakes, rather than just a way to grind combat stats. I'm just using this example because it's fresh in my mind, KCD, Arcanum and the Fallout games are generally great at this. They make you feel like you and these characters inhabit the same world.
- Have different difficulty and outcomes for different builds
This one's pretty simple, and was pointed to by Sweeper a while ago. What's the point of having builds if everyone can do everything? Have quests that aren't doable unless you invest this many points into repair, or that many points into persuasion. Have crowds of tough enemies that can be circumvented by stealth, but not persuasion, and that are more vulnerable to chemical weapons than regular guns. Sometimes, have optional objectives that reward the player for going the "jack of all trades" route, other times, punish him for not investing enough in one skill.
Bottom line: when playing an RPG, you should frequently get a sense of missed opportunity that'll motivate you to try a different build on your next playthrough.
While almost every good RPG does this, I wanna point to Shadowrun: Dragonfall as an example. I've said before that it has a "blockbuster feel" to it, and that's because all the main quests feel like they have their own 3-act structure. Not just in the story, but in the gameplay too. They start off small, setting up the mechanics and general feel of the quest, and gradually build up to a big showdown. They're all memorable, not just because they're mechanically fun but because they serve as a payoff for all the story elements and gameplay mechanics you've been familiarized with.
It's never just "go there and kill 20 kobolds".
The specific thing I pointed out about Underrail's quest design is that it likes to shake things up mechanically. There's the doppleganger island, the bit where you're ecsaping a room that's flooding with mutagen, and so on, but something I find interesting in retrospect is the mech-piloting mission. Throughout the game, you come across burrowers, which are tough enemies that always appear in managable numbers, except in one quest where you have to fight off a massive infestation with a mech that's powerful, but can't be healed. It's interesting because that's a common trope in non-RPGs like Chronicles of Riddick. I'm not sure if taking cues from other genres is always a good idea and Underrail pulled it off.
This point isn't about Underrail specifically, it's about how quests should ocasionally put an interesting spin on the mechanics, UR is just the best example to my knowledge.
Anything I missed? How else would you define good quest design?
Oblivion's quests were boilerplate with the lone exception of the Dark Brotherhood questline which is Hitman in Cyrodiil.
