Edit: didn't see your edit. The responsibility is getting more users in - we aren't going to be hand-holding here. We are looking for experience in growing apps and we need guidance from someone who knows more about this than we do. We don't want someone with a strictly employee mindset and we need to work with someone entrepreneurial in spirit given our early and agile stage.
Similarly for compensation - due to the nature of the role it might be a discussion of a performance-based compensation, but we are happy (and would probably prefer) to pay a day-rate of about £250 for the right candidate.
I phrased the post a specific way because we got so many applicants last time that were just spamming everywhere without even clicking on the landing page - we truly believe this to be an exciting and novel project with great foundations and want someone who is excited to work with us.
I know the kind of person you are looking for. I am that type of person. And I'm telling you there is no way I'd download an app and send my ideas in as part of a job application. I'd gladly do so as a small paid gig during the application process, when we have talked and it feels like my experience matches your needs. But not as the initial contact, no way.
Point taken in one sense (perhaps, we'll see if we find someone great with this post), but (and I don't mean this as a slight at all) the transactional attitude you illustrate in your post is exactly what we are trying to avoid. We want creativity and curiosity!
Is there a role open, with expected responsibilities and a compensation level you can communicate?