Not OP, but TTRPGs. Started after I finished BG3, and talked my friends into playing DnD, with me as a DM. Knew literally nothing, and hyperfocused for months learning as much as I could.

I've prepared a 70 page document for my players detailing every one of my 6 homebrew classes, 20 subclasses, 15 origins (races don't make sense in the setting), and some lore about our ASOIAF campaign (I could keep going for hours about all I've homebrewed).

We're all ready and rearing to go and I'm kind of... Already over it. I'm homebrewing vampire bloodlines ala dragonborn lineages and wild magic radiation and mutation systems on the side but those don't make sense in this setting, and it hurts.

Edit: the worst thing is, I do have people that would be interested in those homebrews, but they're my players and I don't want to spoil them!