You will need to buy the game separately when it comes out. There will be a demo, however, in case you're still not sure whether or not you want to get the game. The game will be sold via Steam, Runics website, as well as through Perfect World entertainment. A boxed version will also be available in certain European territories.
The world is full of Kings and Queens
Who blind your eyes then steal your dreams
...it's Heaven and Hell, oh well