There is nothing sketchy about this - it's just a marketing tool we are using to promote our app.
Then if you're just doing a quiz, why on earth people will forced to download it? You can make a quiz via forms with promoting your project too, I've seen some projects did it in the past.
Indeed, well people use different strategies and techniques and their way isn't a good idea. For some reason people like us seems to have bad idea on it, but I guess those people whose interested have to download it if they undoubtedly wanted to experience it.