I think there's something to be said that there's a certain level of intellectual maturity that's needed to truly enjoy these games.

I grew up with NES Metroid, and despite having read the manual many times over, as a kid I never made sense of the game. I could play it, I could insert the Justin Bailey code, I could move around and do stuff, but I never truly understood what I was meant to do. I stumbled into Tourian one day and promptly got pwned by metroids, and then I never found my way back until I was an adult.

The second metroidvania game I played was Castlevania: Harmony of Dissonance. Maybe it's an easier game -- it's certainly less confusingly open-ended than Metroid 1 -- but I absolutely loved the experience. I deeply appreciated the narrative journey of being trapped in this castle, full of weirdness and twisty passages that were slightly off from each other, having the mid-game bombshell dropped on me, and piecing together a mystery until I was able to find out what was going on. I played it all night, and in a story I like to tell people, the morning after I beat it (and finally got the best ending), as the sun came out, I put on the Aloha de Chocobo music from Final Fantasy IX and it was the most glorious feeling. But this depended on me understanding that I was immersed in a maze, and understanding what I needed to do to find my way out of the maze.

And I've been enjoying this genre since.