The RDR2 environment is an amazing horseback camping simulator. Fishing, hunting, beautiful vistas... bliss
One encounter that stands out in my memory was of driving along a remote road in the middle of the night and coming across a bad traffic collision where a truck had completely crushed a small car along with its driver. Something about the brutal and almost mundane nature of the encounter has stuck with me.
"What was more surprising, though in retrospect it should not have been, was how instantly attached my eight year old daughter became to the game the moment she caught an unlucky glimpse of me playing it. Of course, it makes perfect sense. This is a game where you own a horse, ride your horse, take your horse out into the brush, find wild horses, capture and tame wild horses, and make one of those horses your new horse."
http://jeff-vogel.blogspot.com/2010/12/red-dead-redemption-a...
So the hunting and fishing and birding is fun because the rest of the game contextualizes it.
But it's still a balance between reality and the interesting subset of it; having to manually brush your horse with a mouse would be awful, while requiring that you take your horse to a stable every night would be fine.
The main issue is that to design a decent simulator like that though, you have to avoid basically 90% of modern gaming trends. Fast travel, mechanically-intense play, grinding missions, small-but-numerous subquests, etc are exactly what a modern (A)RPG pushes for, and are exactly how you ruin a game like euro truck simulator. It's the mundanity, scheduling and (some) repetition that makes the game satisfying.
That was in Barbie Riding Club.[1]
As someone who brushes a real horse almost every day, it's not that bad with a mouse.
Ofc, if the game was primarily about taking care of your horse rather than maintanence for riding your horse, it might be fine. But my tastes definitely tend towards the latter.
1. Leaving it out altogether
2. A "brush horse" button that you click and that's the end of it
3. Making the player do it with the mouse
In American Truck Simulator you don't have to clean your truck, but you do have to get gas. Since a horse's cleanliness is more vital, maybe a cleaning mechanic (or at least a button/corresponding animation) should be in the game. Then you have to address the timing, which environmental/time factors, etc. would cause the horse to get dirty, if taking the horse into a lake will rinse it off (wait can our horses swim? Need to check with the dev team). I think I'd have a hard time designing a simulator that would actually be fun. So many trade-offs to consider.
Horse cleaning is important for maintenance, but a non-thought in travel. Thus a horse maintenance game would have brushing mechanics and it would be sensible, while it'd be a nuisance in a game emphasizing travel (even slow travel; feeding/housing your horse would be much more appropriate). But the key I think is to realize what the effect you're having on gameplay is pacing, and the mechanic of brushing or feeding or whatever is just an aesthetic/reason around it. So you'd only simulate so far as to render the pace of the game correct, and no more. So you might have feeding or cleaning, but probably not both in a travel game (it'd slow things down too much, and probably be part of the same operation anyways). A maintenance sim would prefer much slower pacing than even a slow travel game would
I don't know to what extent you can remove risk-reward loops without making it a product that can't pay for its own development.
Wilderness (1985)
https://www.mobygames.com/game/wilderness-a-survival-adventu...
From the sound of it, RDR2 would be a great starting point to build a modern implementation of Wilderness.