One of the growing trends these days is solitaire RPGs -- where people play alone as both player and Game/Dungeon Master. Typically this isn't done by AI but by rolling on various tables (sometimes called "GM Emulators"). Not everbody has the time or even enjoys the extrovert pressure of a traditional social RPG. A related concept is the "cooperative RPG" which does have multiple players but no DM so everyone can play.
Here's a list of some of the ones available (about 10 years old but it gives you the idea)
Here's a list of some of the ones available (about 10 years old but it gives you the idea)
https://rpggeek.com/geeklist/181957/list-of-solitaire-soloab...