The fifa coins industry website has

The fifa coins industry website has also uncovered prototype user interface and in game screen shots of the Ensemble http://www.mmogface.com/ Halo MMO.The screens were briefly available on an Ensemble linked online artist portfolio website.

Ensemble was working on a Halo MMO go back as far as early 2006 when Game Informer claimed the studio was teaming up with Bungie to work on the project.