What would you do to create some of the other themes of Mage? Rather than playing in Dark City, you play Hellblazer. Your sanity isn't in question, your humanity is. Fighting against the isolation/detachment inherent in your adventures. A theme would include "what are you willing to do/lose?"
I've got a few settings for this theme
- Masquerade:Magic, demons, and faeries are real. This is the world of Hellblazer. For reasons of heritage, desperation, luck, or naivity you are able to interact with them. The more magic you gain/perform, the more influence they have. Exposing muggles to your world marks them as targets, the danger roughly proportional to how much you introduce them into it.
- First Contact: They came from the stars, alone and broken. Their influence is profound, but they are fractured. This is the world of District 9, where Earth is changed by alien existence and their tech is behind the scenes in gov't labs and drug lords. Embroiling yourself in their affairs unlocks all sorts of doors, at the cost of isolation with an unfriendly human world.
- A God Am I: You were a nobody, but now you're more than anyone could ever be. This is the world of Akira & Watchmen. Your struggles are commonly beyond the comprehension of humans, and the human part of you is just as uncomprehending of how to handle the power as literal metaphors are battled.