Tips for how to start a game?

I have this game idea that has been stuck with me for a while, and since I am on school break I wanted to see if I could make a demo or at least start something. I thought since my idea is very simple (not even a RPG, just a walking simulator with occasional visual novel dialogue) it wouldn't be so hard. The problem is, right out of the gate, I got too overwhelmed and ended up not doing anything at all.

For context, I have made some pretty long games before in RPG Maker MV, but they were all using presets or modified presets. So the problem isn't that I don't have experience with the engine, is just that-- there is SO MUCH stuff I took for granted.

I don't know what should I do first...is it the pixel sprites? the visual novel sprites? the tile sets? the music? the system????? I don't have any skill issue that's stopping me from doing things, it's just that...what should I even start with??? There is so much stuff to think about like the menu background that I didn't even think about before. Can someone please give me tips on how to manage everything? I am going insane .