Some sites know it as 4, so maybe this will be better here
Because of Tiberium Wars, i often call it Tiberium Twilight, but i also don't know the difference in the meaning of Tiberian and Tiberium.
You can download and install the Worldbilder for free and i think there are some really good Tutorials, that will help you to Work with the Worldbuilder, like this:
http://translate.google.de/translate?hl=de&sl=de&tl=en&u=http%3A%2F%2Fwww.united-forum.de%2Freplays-and-maps-f993%2Fc-and-c4-worldbuilder-tutorial-97690
There is also a lot of feedback regarding playability and atmosphere, so i think you didnt need to play it, if you didnt want, to participat (but sure, it will be harder).
Its funny, that C&C4 is the third EALA Game which is based on the RNA Engine. But you can call it also SAGE 2.0.