Ensemble Studios may have been secretly working on a Halo MMO for Microsoft.
That's according to leaked prototype images found on an Ensemble-linked artist portfolio website by Gamasutra.
The pictures show a typical MMO user interface of chat box, health bar, skill bar and mini-map, with a character sporting the Halo Spartan armour made famous by Master Chief.
A separate still illustrates a melee-focussed hero alongside a magic-wielding character, with yet another image picturing a scenario containing some overturned Warthog vehicles.
The evidence is far from conclusive, but backs up comments made by Ensemble boss Bruce Shelley about work on secret prototypes at the studio, plus job vacancies seeking developers with MMO expertise.
Microsoft's Phil Spencer also told GamesIndustry.biz recently that there were "more than two or three teams building Halo things right now".
Ensemble won't be one of them, as Microsoft has decided to close the studio after it finishes work on Halo Wars. However, parts of the team may cross over into other areas and so keep the dream alive.