You can't copyright a UI.

If that was the case, Sony would've drilled Blizzard into the ground.

Because you can't copyright/patient ui designs? Because WoW's UI is deriviative of the UIs of other MMOs that have come before it? WoW's UI was a design of necessity, all the basic features to play the game comfortably. Other MMOs use similar UIs because it's a good design. It's like asking why Ford hasn't sued other car manufacturers for making vehicles similar in basic design to their original Model T's. You just go with what works.

Interesting. I would have thought it fell under Design law, or is that just a UK thing? (http://www.ipo.gov.uk/types/design.htm)

"We cannot give design right to designs that are commonplace, everyday or ordinary."

UIs
1. Are not a design, they are a function. UIs are not work. Though making a good one may take creativity.

2. UIs are normal in every game, in fact, pretty much mandatory. So copyrighting UIs would be impossible since not just MMOs use UIs that are similar to one another.

So I could make a game that has an almost identical UI to an already established game? As an amateur game designer, I think that's pretty awesome. I was actually working on a game last year and used the UI graphics from an existing game to save myself time. If I am allowed to effectively just draw over their UI elements to make my own, that means I could actually finish the game and release it if I get the time.

I could see Runes of Magic picking up a lot of players. The market for free to play MMOs is huge and the games in that market is usually fairly poor. If this game plays as well as WoW and feels familiar to WoW players, there's no reason they can't pull in hundreds of thousands of players. Since it's free, I'm going to give it a go myself.

Isn't WoW's current interface based on a 3rd party mod that added more skill bars?