This is a really interesting forum post detailing how the GUI has evolved in the hit game Wild Terra. There are lots of screen shots showing the progress over the years.
"After all basic functions of the game were fully prepared, we started to think about the design and style creation for the interface. For this task we hired a freelancer, who had examples of his work suitable for Wild Terra. A budget of the project wasn’t big and we made a deal for a moderate cost, but with a 50% prepayment. Soon enough we got first versions of the interface and determined the visual style, but after this the freelance suddenly disappeared. The rest of the work was finished by Mikhail — our art-director."