I know you specifically asked for not this but its the only game i know that is a good rpg on mobile. You could play old school Runescape. Its essentially single player since there aren’t many parts of the game that require co operation. You will see other players walking around the world and talking but you can turn public chat off so you never need to see anything they say. The game is incredibly light on data usage since it was designed as a browser game in the 2000s.