glad to have indirectly inspired this thread haha
I’m sure there are a bunch, but the first title that comes to mind is Skylight Freerange.
It’s a grandiose, open world RPG entirely made by one guy (I can’t remember if he does the music or not). The series started on PC as an RPG Maker game; the one I played on the PS4 is an expanded version of a later PC release. The series has been quietly chugging along for years; this one is the fourth game in the series, and there’s even two more after this. He even made a Smash clone spin-off with all the main characters!
Aesthetically, it’s easy to see why this is hard to recommend.
The story is not great. The lore is needlessly “mature” and convoluted (I can’t remember exactly, but it all takes place in some alt-future Canada?). But the battle system is so close to being really interesting. It’s a mix of turn based and 3rd person action that’s similar to MMO combat in theory but manages to play nothing like that. It’s not punchy enough to be fun to anyone sane, but I definitely think it could inspire someone to make something really cool if they actually played it.
I now have all the other titles and want to play through them all eventually. I knew so much about the lore after finishing the game that I almost started a fan wiki for the series. (I really wish I did because I remember absolutely nothing now). Maybe the combat eventually gets good! (I doubt it.)
I admire the sheer ambition of someone punching above their weight like this. I get why this wouldn’t appeal to most people, but I wish we had more developers/games like this. It’s true outsider art of video games.