From the Game's Introduction:
Dark Spell is a dice-less, cooperative fantasy role-playing game. By dice-less, I mean that the game involves no randomizers. By cooperative, I mean that authority over the game is decentralized. Every player will share some of the responsibilities of a traditional GM, including framing scenes and playing multiple roles.
Playing Dark Spell is hard to play if everyone isn't on the same page. Everybody has a lot of authority to change and introduce new elements into the game setting. Everybody is assumed to be at the game to have fun, build an interesting story, and challenge one another. The players may frequently be sporting and competitive, and the characters under their control will often be in direct opposition, but everyone's at the game table for he same overarching purpose.
Differences in vision and other issues are bound to come up now and again. At the first opportune moment (say, between scenes, or during a pause in the action) take a brief pause in the game to deal with them out of game. Everyone doesn't have to want the game to go in the same direction, but everyone must respect the vision of the other players. Make compromises.
The inspiration behind Dark Spell is the excellent story hour on ENWorld, "The Tales of Wyre," by the poster SepulchraveII. A game of Dark Spell should feature powerful characters conflicting over big issues. There should be might, magic, and drama. The main characters should have strong goals and strong convictions, and change the world as they pursue their course. Read the ENWorld thread if you need a bit of inspiration.
Dark Spell is not an immersive game. Players will be frequently called upon to operate at the meta-game level, and will need to portray multiple separate characters. Even though there may be many things that an individual does not know, there are no secrets between players in a game of Dark Spell. Don't hide things from the other players. Try to keep your out-of-game knowledge separate from the in-game knowledge of each of your characters. Don't be afraid to state actions for characters that land them in trouble. Trouble creates tension, excitement, and drama. These are good things. Want these things. Want trouble.