The project now is not a rumour.

So in the early future will be a project with Kai Hansen (ex-Helloween, Gamma Ray), Roland Grapow (ex-Helloween, Masterplan) and Michael Kiske as singer.
Roland Grapow has said in a recent interview for a Spanish Website laEstadea.com. An excerpt from this interview is below:

Question: About Hansen and Kiske, there's a rumor of a project. Is that right?

Grapow: "It's not a rumor, it's true. We're just waiting for the right moment. We gathered together two or three times in the last two years. What happens is that Michael doesn't want to do anything with too much hard rock or too much heavy metal, too much dark or negative, he wants to do something more happier. So, probably, when I finish the tour with Masterplan, I'll begin to write some tracks for Mike. Kai too, we'll see what will come out. But, once and for all, we will do something".

Question: This project have a name?

Grapow: "No, not yet! Perhaps it will be titled Helloween! (laughs). No, it's a joke, at the moment we haven't thought of any names because we haven't planned yet. Now we only want to write a few songs which we feel comfortable with, that Michael doesn't find negative, but we all love. Because we don't want to make a Kiske solo album with two famous guitarists from the past. We search for music which speaks for itself without any need to be aggressive or negative".

Source:	michaelkiske.net
Band profile:	Helloween