Let me refer you to David's post in this thread:
The Diedne supplement will be an official part of the game line, and the intent is, as much as possible, to make the video game itself canonical.
The folks at Black Chicken Studios are very enthusiastic fans of ArM, and they are passionate about making the video game true to the RPG. From the first time I talked on the phone with Larry (he's the guy doing most of the talking in the KS video), it was clear that he is extremely familiar with the game and has a clear vision of how to port it into an engrossing computer game experience. It won't replace the tabletop game by any stretch, but for those of us who enjoy the game and the setting it will give us a new and fun way to explore it.