web browser, and Microsoft announced the upcoming Project xCloud, leveraging Microsoft Azure technology. At the Game Developers Conference in 2019, Google officially announced its cloud gaming service Stadia, which officially launched on November 19 of that year. In May, Sony announced a partnership with Microsoft to co-develop cloud solutions between divisions, including gaming. Apple Inc., which makes the iOS platform for iPhones and iPads, had looked to block cloud gaming apps on its service in mid-2020. They argued that cloud gaming services allowed developers to add games onto the iOS system that bypassed the normal checks they perform on any app before it is added to the App Store, and thus violated their terms of service. However, in September 2020, Apple altered its rules that allowed cloud gaming apps to work on iOS, with restrictions that each game must be offered as an individual download on the iOS store which the user must use before playing, though catalog apps as part of the service can list and link to these games. Both GeForce Now and Stadia announced plans in November 2020 to release iOS versions of their streaming services as progressive web applications that would be run through a Chrome or Safari browser on iOS devices, as allowed for by Apple, to support cloud gaming. Microsoft has also announced plans to use a similar approach to bring the xCloud game streaming technology to iOS via the browser sometime in early 2021. Amazon introduced its own cloud gaming service Luna in September 2020. Games on the service will be offered via a channel-style subscription service, with Amazon's own games and those from Ubisoft available at the service's launch. Asus and Intel announced ongoing hardware supply, research & development and software optimization alongside Boosteroid cloud gaming platform in November 2020. Nintendo currently has games on Nintendo Switch that primarily run on cloud gaming because their systems are not powerful enough to run them otherwise (or to avoid porting costs), such as Control, Hitman 3, Marvel's Guardians of the Galaxy, and the Kingdom Hearts franchise. Future GPU resource sharing A proposed method to improve game streaming's scalability is adaptive graphics processing unit (GPU) resource scheduling. Most cloud gaming providers are using dedicated GPUs to each person playing a game. This leads to the best performance but can waste resources. With better GPU resource scheduling algorithms, if the game does not fully utilize that