Activision Blizzard acquisition will no doubt boost subscribers further.
Game Pass now has over 25 million subscribers, across both Xbox and PC.
Once the takeover deal closes, both new and old Activision Blizzard games will be added to the service, which will increase its value for money considerably.
"We also announced today that Game Pass now has more than 25 million subscribers. As always, we look forward to continuing to add more value and more great games to Game Pass," says Spencer.
Last year, Microsoft bought Bethesda parent company Zenimax for $7.5bn and swiftly added its biggest titles to Game Pass: The Elder Scrolls, Fallout, and Doom included.
This was the biggest gaming acquisition in Microsoft's history, until Activision Blizzard for a staggering $68.7bn.
Sony, meanwhile, are rumoured to be releasing their own Game Pass equivalent, codenamed Spartacus.
Spencer even commented on the reports of Sony releasing their own service.
"So when I hear others doing things like Game Pass or coming to PC," he said, "it makes sense to me because I think that's the right answer... I don't really look at it as validation [of Xbox's strategies]. I actually, when I'm talking to our teams, I talk about it as an inevitability."
While details of what Sony is planning are unknown, the inclusion of Activision Blizzard games on Game Pass means competition is stiffer than ever.