saved you a click: "We did nothing to promote the bot. No ads. No paid promotions. No splashy launch. We just put it in Kik’s Bot Shop and waited. (Full disclaimer: We work for Kik, and Roll has been our side project.)"
That's a little misleading. What they did well was keep the bot simple.
"1M users without promotion" is also misleading without "By the way, we run the platform it operates on."