He is just asking for ways, should he want to, to incentivise a less gamist approach. I'm using that term loosely. So what are the benefits of washing, splurging at a tavern, eating well, socialising with ones preferred gender, maintaining your equipment, updating your maps, acquisition of clothing, resting your horse, good grooming, paying for massages, sharing a decent drink...
Xanathars addresses some of these concerns, others not.
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Plenty games have additional conditions that do not exist within D&D. I believe Torchbearer has the Hungry condition. There is no great harm to the game by introducing a Dishevelled condition.
But I'm not sure that introducing a new condition, and more generally establishing
benefits for washing, eating well, etc, will make the game less
gamist. It just seems to be establishing new avenues for tactical play.
A friend and I were talking about how to run a successful game focused on treasure hunting in 5e and it led to a discussion on how players rarely seem to do things that real people do.
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This led to a more broad discussion of behavioral realism in RPGs, primarily about how players tend to operate largely in the game space when it comes to the very basic, human needs and desires and behaviors that rule our day to day lives.
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How do you try and encourage players to play like "real" people, who just want a bath after a sewer expedition or are willing to throw away half their earnings to impress the bartender?
I'm not sure, but you seem to be talking mostly about fairly traditional D&D play, with two features (which other posters have also noted):
(1) Treasure is essentially a PC build resource, and so there is no incentive to spend it on things that don't contribute to PC build;
(2) The fiction of bathing, eating etc plays little or not role in actual game play, It's merely distracting colour.
I mostly play games where at least one of (1) and (2) does not hold. I think (2) is especially important. Just to give one example, from an old Rolemaster campaign: when one of the PCs had spent all his money on the magic-enhancing drug to which he'd become addicted, and hence couldn't afford to maintain the lease on his personal villa, it had a big impact as his aspirations for social climbing collapsed, he lost his base of operations, and ended up a degraded pauper dependant on the charity of (and highly subject to manipulation by) a fellow PC.
That was a game in which housing and social position mattered because they were (among other things) central to the actual play of the game.
EDIT:
folks are focusing too heavily on the "bath" as an example. What I am talking about is acting in ways that resemble people rather than stock characters. Making decisions based on need and desire and personality and physical and mental (dis)comfort, not just what is most tactically superior, mechanically satisfying or even narratively appropriate.
In my Prince Valiant game the three PCs have all married (remarried in one case - that PC started the game as a widower; one of the othe PCs is his son). There was at one point a rivalry between two of the - some of which was played out in mechanical terms -, but it was ended when one found himself married to the daughter of the Duke of York somewhat against his own better judgement. That same character has also come very close to having an affair.
In this game it's also the case that time - week, seasons - often passes simply by narration. The PCs wear fine clothes on appropriate occasions. Etc. I think it has much of what you're looking for.
Compared to traditional D&D, the system has social resolution mechanics, factors emotion and relationsihps into resolution when appropriate, and makes the knightly life (as seen through the lens of Arthurian romance) central to play. There is very little wargame feel to the mechanics or the fiction.