Gears of War is a huge franchise for Microsoft, and Gears of War 4 is a huge game for Microsoft going forward, so Microsoft starting off their conference with this game was probably a smart move. To open the event they showed off a new gameplay trailer to which you can find below, and followed on with some exciting announcements for those interested in the game.
As a starting reveal Gears of War 4 will launch for Xbox One and Windows 10 on the same day, if that is not satisfying enough then it does get better. You will only have to buy one copy of this game, and immediately it will become available on the opposite platform such as buying on Windows 10 means you own it on the Xbox One also.
If that is not good enough Gears of War 4 is also going to feature cross-play which will feature across all co-operative modes between the Xbox One and Windows 10.
Gears of War 4 will arrive on October 11th.