Making games of a graphical nature doesn't really need a GUI library. Just set up an OpenGL rendering context, or a 2D canvas in any way possible (Java, Obj-C, C#), then you can easily use C for the rest.
How good are you at C? If you have spent quite a while mastering it, then I don't see a problem why you cant use it.
Especially since the popular way to develop games nowadays is using the Component Entity Model which favors composition over inheritance and so using an OO language is not necessary.
That said, C can handle object orientation perfectly fine which you can see in pretty much any C GUI library (Motif, Gtk+, etc..)
In other words, you don't need to spend time learning a new language and you can start making software. 80%+ of the UNIX world writes user-land programs in C so it is certainly capable.