Then, when you're comfortable, maybe transition to some HTML games to be made in your browser of choice. These will get you used to working with graphics.
Alternatives to Unity3D are game engines like Gamemaker (paid) and Unreal Engine (now free!).
If you want to go even further, I would recommend learning either C++ or Java (I prefer Java, but that's probably just a question of preference). You can learn the syntax for those languages, then learn about a graphics module for the chosen language.
The reason I didn't suggest learning python instead of C++ or Java is because, although Python is a high-level language, it isn't built for programming user interfaces - especially with the complexity a game would bring.
Hope this helps!