The Chewiness of an RPG

I'm just curious, what elements do you look for in a game that might superficially be called an RPG? I mean, we talk about the degree of agency that we have over the growth of our character. We talk about being able to change their abilities, to change their equipment,. To guide their growth in a way that you do not see necessarily in other genres. And I know for me at least that's a really appealing aspect that I like to see in my games.