Why does everything I start turn into an epic?

So the pocket size challenge was amazing and inspiring, and I've started writing something that I'd been brainstorming before. (dystopic Saiyuki AU, fwiw.)

I'm feeling way less rusty, which is great. But somehow it has already morphed into an epic! I want it to not be so big, because I'd actually like to finish it sometime this century. (unlike everything else I've been struggling to finish in the past two or four years, duuur.) I've got the whole plot drafted and some key scenes down, but there's a lot more that I want to do before it's done, and I'm kind of struggling to figure out what to cut and what needs to be in the story, but I'm still at the point where all the ideas still seem good and doable.

Anyway, I'm going to keep working on it and maybe, eventually, I'll have something to share.

~later