Don't think it can be Duex Ex as duex translates to two which is obviously excelled by one.
In fact I don't believe it could be any one game no matter how awesome because this wouldn't please everyone.
None of us care about the sites beta status and a site redesign would be nothing to get excited about.
I have to follow others here who side with this being a new publisher, I believe it will be Microsoft for three reasons; The background image has a Halo feels to it; secondly software compatibility is a hugh obstacle for many people looking to upgrade their O/S so they benefit from this two-fold; Lastly and most obviously Microsoft are, from a size perspective, like it or not ,unexcelled.
The only problem with this analogy, and it's a big one is that it wouldn't really excite anyone in any way other than showing us that GoG mean business!