First, you need experience. It's very good that you have a specific idea, but you also must have an idea on how to implement it, so you must be a professional programmer to accomplish this task.
Second, big games are mainly created by large teams of designers, programmers, testers etc. so there is a very low chance you will accomplish the task just by yourself.
Third, it is not so easy as you think to create a big game. Again, you need to be a very experienced programmer to write even a very small part of it.
Check this thread (just for reference):
http://www.dreamincode.net/forums/showtopic54319.htmPS: I guess you should post threads related to game programming here:
http://www.dreamincode.net/forums/showforum69.htmThis post has been edited by PixelCard: 4 Aug, 2008 - 11:47 AM