tomimt: Yeah, MS has for ages wanted to become more intepended of other retailers, be it games or other software. If they could they'd cut out all the other retailers out of the loop completely.
Still they're not dumb enough to avoid Steam! :)
I could say that they're losing money by not selling their old titles (that are not even being used) but something tells me that they have some developers making HD version of those so that they can sell at a higher price...
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As for the topic, i would say 2k > SquareEnix > Sega.
I would even say that i wouldn't be surprised to see new games released here from Ubisoft (M&M games), Paradox Interactive or even EA (yeah, maybe not). My train of thought? Well, let's be honest here, bundles devalue games, if you check the big publishers humble bundles you will see that some of them appeared here therefore i could see those that i've mentioned also appearing here, not sure about sega since they're stubborn.
Btw why doesn't Paradox Interactive has more games here? I would imagine that the audience of gog is good for selling grand strategy games...