Be glad that you are 13. Think positively about your situation. What this means is that you are going to have that much more time to gain experience before you "leave high school/enter college/leave college".
To reprhase your statement to give you a better idea of what you're going to have to do: "Not even a graphics game, just a text based game, you could be able to create one after about a month of programming, and that doesn't include the time you will have to invest into to actually creating the game."
It all depends on well you can grasp the concept of programming, and how much time you invest into it. Being your age (my age as well, 16) it may seem hard to invest that much time into something where you won't even see "cool" results for a while. Try to keep yourself motivated by doing fun, little programs. Personally I don't find it fun to copy the text out a book, compile the code, and then run the program. I may be learning while I'm doing it, but I find it much more enjoyable to create the program myself. However, I still do both. The programs don't even have to be that extravagent; simply creating one is enjoyable for myself.