Xbox One and Windows 10 integration.
During the event, the firmâ€™s head of Windows Terry Myerson said Universal Windows apps will be coming to Xbox One with Windows 10 and Xbox boss Phil Spencer eventually took the stage to discuss the Xbox One app.
The app brings in your friends list, allow you to comment on the activity feed, and it will list Xbox games alongside Steam games.
This was demoed when Civilization: Beyond Earth was launched, and users will be able to use DVR functionality to capture gameplay.
A DirectX 12 benchmark was present in the demo, and it said to run much â€œsmootherâ€ than DX11 and power consumption is half that of DX11.
Lauran Carter from Lionhead took the stage to show a demo of cross-platform play between PC and Xbox One in Fable Legends, which will be released on PC.
Forza was also shown being played on a Surface Pro 3 tablet.
Xbox One exclusives can also be streamed to any Windows 10 PC or tablet, Spencer announced, adding that the firm plans to â€œtreat Xbox gaming on Windows 10 with a passionâ€ equal to that of gaming on Xbox One.
More gaming news from Microsoft will be announced during GDC in March and throughout 2015.