I think if there was an App ever to come out (wouldnt see the point since the website works fine), I think Daniel or RHavar would announce it beforehand.
That definitely, yes. And most importantly, the app would also be advertised on the official bustabit page, which of course is not the case with this one either, which already points to a scam attempt here.
Presumably, the app simply wants to steal login data and thus to drain the balance from the account. A very simple and very effective attack, unfortunately ...
And the website itself works as a web app quite perfectly. When you are visiting the site on chrome on android, you get a message to add the website as app on the homescreen. If you do that, you'd receive an app like icon with bustabit logo that opens full screen directly to the Bustabit and there's no way to differentiate it from an actual app.