fossilapostle

This fantasing is very common among all people of all ages. I wouldn't say it's a symptom or cause of any mental illness unless you're having trouble distinguishing the real from the fantasy, or you're spending an unhealthy amount of time in your "fantasy world."

One suggestion: Have you every considered writing down these fantasies? Keeping a journal, or however you'd prefer to do it, is a great way of dealing with these types of things. Also, if you're fantasies are that detailed and complex, maybe you could write some interesting stories.

After all, Tolkien (the man who wrote the Lord of the Rings books) invented his fantasy world originally to deal with the stress of being a soldier in World War 1. He came up with, like you, an incredibly complex society different from our own. Far from being a mentally ill though, he used his fantasies to write his books and became a very succesful author in his own lifetime and after.

A lot of things in life are good or bad depending on how you look at them. I think your fantasies could be bad, neutral, or good depending on how you choose to percieve and deal with them. Or to put it much better than I could: "The mind is its own place, and in itself, can make heaven of Hell, and a hell of Heaven." -John Milton.

Good luck!