Let me have a shot at this:
I will not discuss the validity of the code you entered or your log messages simply because you’ve started this in bad way since the very beginning. Even though you put the right code in the file, it still may not work. Trying to compile new C++ code through the editor is a no-no; it’s been clearly told many times in Epic’s own C++ tutorials that you can find online here: Introduction to Programming | Live Training | Unreal Engine - YouTube and here: - YouTube
The editor can only compile new code in existing functions and part of your error messages are due to this. Add a variable or new signature and BOOM! Instant incomprehensible messages will spit out in the error log. You need to close the editor, compile it natively then load it in the editor. Larger support for a more “intelligent” hot-reload from the editor is not due before 4.4 or 4.5, I believe.
Also, you’ve added a new GameMode code in your project when you already have an existing GameMode blueprint that might get in conflict with it. It might compile but will it load ? I’m not sure. You’ll need to delete the blueprint and create it again based on your new class without forgetting setting it up as a default blueprint and set all the other classes that need to be attached to it just like the original. Personally, I’ve never tried to add C++ to an existing BP project because it’s so much work. The reverse, however, is trivial.
What I suggest is to follow these videos (try the first one, it’s short and to the point) and learn C++ programming and compiling under Unreal 4 with them, even at its basic level, then start from scratch with a C++ program. You’ll have a default GameMode where you can put the pause code and carry on in Blueprint. Yes, you can mix C++ and Blueprint this way. But you’ll also have a C++ program ready for any additional little trick you might find helpful in the future.
Regards.