Thanks for the good clarification on that. Yes, I was mostly joking about Myst not being an adventure game. I didn't think about the fact that people less familiar with the genre might take me seriously.
But yes, Myst is definitely an adventure game and a very popular one. All I really meant to say was that Myst did not start adventure games or even make them popular. They started way before Myst and were already very popular. But I did not mean to imply that Myst was not a popular game. It certainly was. And again, yes it is an adventure game.