Or one could make an RPG sequel or spin-off based around this concept. You build up a roster of adventurers, then they fight under AI control.

There are actually some turn-based RPGs that do something like this. For example:
* Dragon Quest 4: In the original version, once you reach Chapter 5 you can only control the legendary hero, while their companions are solely AI controlled. With that said, it's actually a rather advanced AI for an NES game, and you can equip your companions and select a tactic for your party to use. (For remake versions, if you want a more authentic experience, just avoid using the Follow Orders tactic in Chapter 5. It gives you a feel similar to the original, even if you take advantage of the ability to set different tactics for each party member.)
* Wizardry 4 allows (in fact, requires) you to summon monsters, but during combat you only get to control Werdna. Your summoned monsters use an AI similar to the enemy AI of previous games, with a few tweaks (summoned Priests will heal you if you're injured, for example). Note that this game could be argued to be an adventure game disguised as an RPG, and note that as an adventure game it is quite hard. Also, the game isn't always fair, like when enemies cast MAKANITO.

I've seen a couple games (at least one's on GOG? I forget the title) that try to take this premise. "You try to match adventurer's skills to what the map shows needs to be done". I think at least one of them was roguelike. Haven't played.. But yeah, that same idea. I just think "fleets" might make it smoother in play and differentiate it more from "fantasy tropes". "Epic Manager" was the title of one. Not so great reviews on Steam.

Aha, Epic Tavern is the GOG one (Indev)

But there are the "Gratuitious Space Battles" games that are similar, but that I didn't like. They're "set up and then press play" but take too long. But they were too rock-paper-scissors. And I could never make any progress toward winning.

But, yeah, you know how I feel about "0 player games". These straddle that line but are still player-driven games.

John Conway's Game of Life could also be an example of a "set up and press play" game, though because the game is Turing-complete, it's not possible to know whether or not the game will reach a steady state in a finite amount of time.

Wondering what a sequel to it might be like.

(I know Pac-man got some sequels that are very strange, including one on the SNES where you don't even control Pac-man directly!)

SWAT 5, but it's a point and click adventure starring Sonny Bonds.

Hollow Knight 3, but it's a hybrid of an incremental game and an RPG,

That is, you level up like in an RPG, and there are enemies to fight, but the game continues to run while idle, and you continue progressing while idle, gradually gathering XP and Geo that can be spent in order to speed up the rate at which you earn XP and Geo.

Alternatively, Hollow Knight: Rogue Hollow. This game would be a turn-based roguelike, where you explore a randomly generated version of Hollownest, in an overhead view perspective, with turn-based gameplay, and of course the other things you expect to see in a roguelike.

Something less radical might be La-Mulana 3, but it's a pure adventure game; the whole action platformer aspect found in previous entries of the series is gone.

On that note, of course we could have ActRaiser 3, which would be a city builder, with no side-scrolling action stages. You're just a god who builds cities, solve their issues, and lets them flourish. (The city building mechanic is found in the original ActRaiser, which does have side-scrolling action sequences, while ActRaiser 2 doesn't have the city building, so for ActRaiser 3 how about we throw out the side-scrolling action sections and leave just the city building?)

Reading this again, I really want to see something like this. Pirates Inc or another warrior management sim sounds awesome. Maybe JRPG elements using the power of friendship to kill god.