Hi! I have an Android Game that is succeeding and now I want to launch it for iOS. Should I have two projects, one for Android and another for iOS, or can I do it with an only project? I use Google Play Games and I want to use Game Center for iOS, and I don't know if it all could work in a single project. Thanks
Same project, just switch platforms. And you can have all that platform-specific features in the same project, just activated as appropriate.
Use one project and make sure that you encapsulate the platform specific logic in complie preprocessors: https://docs.unity3d.com/Manual/PlatformDependentCompilation.html