In newer engine versions the GameMode.cpp and GameMode.h files are no longer created automatically. Almost everyone deleted them anyway so they were pretty pointless. If you need one simply go into Unreal Engine and create a new C++ class of type GameMode.
As for the 52 “projects”, I assume you mean all the extra files in your solution under the Programs, Rules, Visualizers folders. Again, this is only there in newer UE versions. You do not need to worry about them, just press ctrl + left arrow to close them.