Using C#, C++, C or GDK is fine for Gameengines, but what about the Launcher?
if you implement your own launcher you probably can do this in any language to be more platform independent in the future. But this application can not talk to the spatialos backend (for example to get the client download or simply get the login token for starting the client.
Sure in theory you can use the low level c api, but this is kinda overkill for these simply tasks.
And there must be any kind of API your spatial launcher uses to download, authenticate and login the client against the spatialos backend. (alread read about this in another post, that this is simply not public).
Thanks And keep up your good work.