GeForce Now announced a new feature where publishers will be able to opt-in to make their games available in the service. They also provided a list of available games and some that will leave after May 31, 2020.
GeForce Now is a game streaming service that serves as an extension of a PC gamer's hardware as opposed to being a platform of its own. At first glance this may not mean much to you but the important distinction is that the service does not require another purchase of the same game that you already bought on PC.
This approach rubbed many developers and publishers the wrong way as they could no longer double-dip on the same product. Therefore, many games were pulled initially as publishers and devs cited GeForce not asking their permission as the reason for doing so.
On May 27, 2020, GeForce Now announced a feature that lets studios and publishers opt-in for their service and released two lists that support it. One list includes the games and other the publishers that are committed to it.
The current catalogue is about 500 games strong and subscribers can play these immediately. More games will be added every Thursday and GFN stated that there is a total of about 2,000 games committed to the service. Furthermore, over 200 publishers have chosen to stay with the service. You can find both lists on the opt-in announcement page .
There is also a list of games that will be pulling out on May 31, 2020. It includes some oddballs such as Heroes of Newerth and Islands of Nyne: Battle Royale. The latter is a dead game while many believed this to be true for the former as well but apparently there are still some people playing HoN.