What you have access to is far less important than what your skills are.
So, are you a programmer? If so, what programming languages and libraries do you know?
Are you an artist? What kind of artist?

Don't do C# then, unless you want to learn it anyway. Stick to what you know first. And don't worry about art; once the game is actually programmed and running, THEN you can find an artist you can talk into making content for you.

So the next step is to sit down and think: what kind of game do you want to make? What sort of things do you want to be able to do, and what can you get away with not doing? You say you want an RPG; what structure, story, characters, and kind of gameplay do you want? When you write this down, it's called a design document, and it seems that all the cool game designers use them. You don't have to know utterly everything in advance, but you DO need an idea of what kind of functionality and limitations you want. I've tried writing a game on the basis of "I'll work out the details as I go" and the results were... not pretty.

I would also recommend starting off tackling some smaller, less ambitious projects before making your Great American Game. You may think "bah, that's too easy, too uninteresting", but I'm sure you'll run into new and fascinating problems you never even knew existed. [grin]