While I love the idea of the game, and am glad a developer is actually requesting feedback BEFORE developing ideas, I just had to laugh out loud at this particular description....
They have exceptional hearing due to the elongated, pointy shape of their ears.
Last I checked cartilage has no special sound enhancing properties
But then again.. this is fantasy I suppose.
One other item I would highly suggest if you expect this to be more than just a mobile game, such as the PC version you mentioned; It's too 'generic'.
For a mobile app I think people will play almost anything since there isn't a lot to choose from. But from a PC perspective, I haven't seen anything here that honestly I'd ever even think of buying. Other than the instant-switch class ability, everything I've read has been done before.
I'm not trying to put you down, but I think trying to make a PC game AND a mobile one is a mistake. PC games these days are monsters. The cost and effort put into a game like this will be extraordinary.
I've been playing fantasy/mmorpgs since the first days of Zork and Ultima (the original) and back in college ran more D&D games than I actually care to admit. I've seen just about everything and honestly when I read about a game (pc or mobile) that has a handful of classes, and basically fit into the same old Tank/Wizard/Healer basics, I almost immediately get turned off. You need to find something that makes your world stand out.
I know that's probably not what you want to hear right now, and I'm sure people will bash away saying I'm being cruel, but you're asking for honest feedback.
Bottom line is you need to set your world apart from any others already out there, or in development.
Take for example the fantasy novel genre, which is much the same as fantasy games these days. One particular author comes to mind right away of someone who set their work apart, his name is Brandon Sanderson.
Like fantasy games, novels are also tough to have stand out, but somehow each novel he created was unique in some way. He specializes in what one would call 'magic systems', in that each novel has it's world's technology/magic based on something simple yet unique. No other novels have anything similar to his. I thought of your Runes as perhaps something very similar, a typical staple of fantasy , but perhaps turned on it's side.
I won't go into details about his books, but if you get the chance go read them, or at least the synopsis of them on various sites. He's several series out there "Elantris", "Mistborn", "Warbreaker" and soon a new one. You'll see immediately why his books are popular even among the fantasy genre.
Clockwork Rune needs something like that, especially if it's going to compete in the PC world.
Again these are just thoughts based upon what you've posted here and on your site. We've not seen the engine or gameplay mechanics, so who knows, they might be enough to stand out, but from a pure story & class perspective, I'd highly recommend revisiting some things.