Winning the game by being well-rested

I have long believed that the perfect RPG would reward the PCs for getting a good night's sleep – and penalise them for a bad enough one.

There are many upsides to doing this.

1. It's realistic. In my experience, getting particularly good or bad sleep could have a +/- 50% effect on your baseline competence.
2. It encourages roleplaying. People want to get a good night's sleep. Now characters want to get a good night's sleep.
3. It incentivises investing in comforts and nice-to-haves. Without the carrot and the stick, most players tend to default to only getting functional equipment.
4. It adds more choice to campsite selection. More choice is better. (I think it was Peter D who suggested: concealed, secure, or comfortable; pick one)
5. You can tie it to character injury. In HP-based systems, characters tend to either be fine or dead, resulting in confusion about what HP and damage really "are". Well-restedness is pretty much a score of overall condition, so being wounded can reduce the same score. Now it's actually more difficult to jump around on a stabbed leg.
6. You can tie it to character morale. Generally, telling players how their characters feel is a bad idea. Telling them they must act some way as a result is disastrous. But a hard rule like "a character who sees a friend die loses 1 point of overall condition" is non-intrusive, assuming you don't allow sociopathic PCs.
7. It incentivises problem-solving. To get the best outcomes, you need to acquire and carry around more creature comforts, even through hard terrain. So now you have a to-do list and some logistics to work out.
8. It encourages having a bunch of attendants (lackeys, entertainers, back-scrubbers, cooks, night watchmen, etc). This is in keeping with commonly emulated genres like "low-technology fantasy", and opens up new kinds of gameplay.
9. It makes the weather feel real. Most of us are well insulated from the effects of weather in 2025. Travelling, sleeping, or making a meal in bad weather is really rough going. 

and

10. It's also a soft progression system!

Characters with more resources can spend them to improve their day-to-day efficacy.

Characters who end the first game flush with cash might be able to get good provisions and nice camping gear, and secure a future +1 when there's fine weather and uninterrupted nights. Later, they might hire some camp drudges so they can get more rest per day, porters to carry their extra stuff, and maybe a proper cook. They're looking to get that +2. By the end of the campaign, expect everyone to travel with fine silks and furs, feather mattresses, bevies of personal chefs and butlers, vintage wines, and magical solutions meant to ensure good dreams, chasing that +5.

(Of course, if you want your normal "levelly" game, you can turn it into a treadmill: characters get used to the finer things, and their baseline expectations slowly creep up, so the bonus never gets too big)

I've had worse naps. (Artwork via www.lustigesrollenspiel.de)

How to get a good night's sleep

I think this metric is dependent on six things:

• Being sated (not hungry, thirsty, etc)
• Being comfortable (resting in a quiet, comfortable place, in shelter, at a nice temperature, etc)
• Getting enough sleep and enough down time
• Having creature comforts (indulging in vices, enjoying entertainment, being with friends, etc)
• Being safe
• Being healthy (not injured, cursed, ill, in shock, etc)

Some games have relevant mechanics (like systems for dehydration or sleep deprivation), which this approach could either subsume or integrate with.

Mechanically, how does it work? Is there an individual character roll depending on the factors? GM fiat? Player-facing prescribed requirements for each tier? The implementation will of course differ with the system.

So will the outcome. Games with a single central dice mechanic obviously get a dice bonus or malus. Then it's just a matter of magnitude and deciding which rolls it applies to (I think you could make a very good case for "all of them").

Final thought

You might have noticed I didn't call this "the INSERT_NAME rule". My thesaurus failed me.

Fettle and Invigoration are awkward. Condition or Vigour would be good but tend to be reserved game terms, so might be confusing. Words like Well-Rested and Energised don't cover the negative cases. Restedness is apt, but clunky.

Freshness is pretty good (except for sounding like you're in a supermarket).