But more to the point, what rpgs do you know that do a good job at this?
Even more to the point, do you know of any other rpg that is so heavily basing its challenges on resource management, yet allows players to trivialize that management by simply saying the magic words "let's take a rest"?
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I see two fairly obvious solutions. Yet, for some reason both are considered completely unacceptable and have zero rules support.
One: the PHB says you can only rest in specially designated spots, like a sanctuary, or home, or an especially cosy countryside inn. This then gives the adventure control over when and where rests are allowed, thus creating true challenge: "will you be able to clear out the Critter Caves before you run out of resources?"
Two: attrition-based challenge is downplayed. Every encounter is evaluated on its own. The adventure assumes parties can rest pretty much whenever they want, so the level of challenge assumes a reasonably recently-rested party. All fights doesn't need to seriously threaten the life of a party member, but if a fight is a completely foregone conclusion, the DM is encouraged to simply narrate the results instead of wasting any time.
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The other fantasy rpgs I like all use solution #2. Not so much by actually making sure the bad guys are dangerous enough (far from it actually), but by not being level and hit point based. This means pretty
much every fight has at least
the potential of becoming really dangerous, just by the default of how combat and damage works when you don't have a hundred hit points. Compare D&D at level 1 - nobody has these problems at level 1!
It would be cool to have a published adventure that is built on solution #1 though. Where you essentially would have to finish each node of Princes of the Apocalypse with, say, two* short rests. And you could only take a long rest, one* long rest, before and after each one. That would mean you have eight short and four long rests before we check: did you succeed or did you fail?
*) Completely made-up numbers, by the way. I did give PotA a quick read-through back when; but I have absolutely no recollection of how quickly you would clear out each node...