xCloud will be included with Game Pass and run on Android devices.
Microsoft had just announced more details surrounding their new xCloud gaming service. In addition to being able to play any game in their game pass library for a monthly fee, the cloud service will be free for Ultimate Game Pass holders. The ultimate game pass subscription costs just $15 per month.
Microsoft states that most titles in the library will be available on xCloud which includes popular games such as Gears of War, Halo, Grounded, Destiny 2, and upcoming games like Tell Me Why. Microsoft revealed a few weeks earlier that all their upcoming games will be immediately available on Game Pass.
xCloud will not be available for PC at launch and will only support Android phones and tablets. They have not yet addressed the situation of iPhones or iPads.
Microsoft also has some hardware displayed on their website that is designed to transform your phones into a full gaming experience by adding proper controls. This includes the Razer Kishi that mounts your phone and their mobile gaming clip that hooks your smartphone onto an Xbox controller.
Microsoft xCloud details can be found here