Welcome, [@Bastian]! Not knowing what this hobby is called is a struggle many of us share, I think. I first started role-playing in the writers forum in Neopets when I was around 14, and I believe more people certainly came from places like that. Poke around the Guild, the site is pretty active still. I'm glad you found this place, I'm sure you'll find a good writing partner or group again. Let us know if you have any questions, everyone is quite nice. We also have a discord server if you wanna chat with folks in real time -- you'll find most people are around your age group there; the invite is on the menu at the top of the page.

Anyway, good luck and have fun!