I'd believe there are some people that just keep their interest to whatever they're in. I know that sometimes poking into another rp might end up with them actually interested in it as well.
There's also continuation in a way. I only see a new face or two rarely, as it's normally the people that have participated in my games in the past playing a new one.
If you have everything on your side, like plot, how you'll handle choices, and other such down, then it's just waiting for people to take that chance.
Also, I don't think Rumia's is very nowadays. There's about 5 people that frequent it and it's games, but probably a few more rare faces.