Four professions: warrior, mage, assassin, cleric and street musician each one with specific ways to achieve goals and unique quests. Professions are choosen when you advance some levels in the game, not when creating the characters. Each profession will provide a specific gameplay and story.
Full 3D isometric view: zoom and camera rotation besides the traditional scrolling. Third person camera view as a plus
Rich skill tree: lots of skills to get lost and make you mourn the points wasted in useless stuff.
Real time combat. Even when combat will be in real time, it is a not a crazy Diablo-like click orgy. You issue commands, like attack, some of which your character will continuosly perform until you issue another command.
Open ended, fantasy based, non linear plot. The Ark introduces you to the world of Elymuria, during a conflict of epic proportions: the war against daemons. Choose your side and decide the destiny of Elymuria. Will you serve the old Gods, the daemons, or will you be nobody's puppet?
And many more! (This basically means: we have no idea about what can we really do)
Warning! This is work in progress. So, definitive things could be better (or worse).