Today, I'm going to add NPCs! I really want to get these guys in, which mostly involves creating a lot of different combinations of clothing, facial features, and body types. My feeling is once I have the NPCs "placed", I can start to think about other gameplay features. I suppose pretty soon would have to be shooting your gun, those sort of interactions. But having the NPCs in place will give me an excellent framework for building the game.
I usually like to design a "world" first which is sort of an organic structure with people, places, some backstory, and so on. Then inside that, I can create the actual game. That's what I'm doing with LUI and that is why I'd rather get the NPCs in before I start to add additional gameplay elements.