Szilard's comments about magical difficulty based on plot significance went pinging around my skull and brought together some stray elements. Let's see...

This game is about characters who discover that they belong to a layer of reality higher, deeper, or other than the world they've always known. Credit here to Paladin and its broad treatment of the "holy warrior" theme; in the case of Real Souls (which obviously needs a much cooler name), it's the element of unseen layers of reality that's crucial, whether the characters are ghosts, the users of a simulation, prisoners of someone else's simulation, or people fleeing an unresolvable tragedy in the style of Iain Banks' The Bridge and the later issues of Steve Moncuse's comic book Fish Police.

Within the known world, some reasonably self-consistent set of rules applies, whether it's fairly naturalistic (The Matrix, The Thirteenth Floor) or highly unrealistic (Fish Police). What people from the unknown world possess is the potential to transcend those rules. As they acquire insight, they shift over to a system where difficulties are based on how connected to the unseen world a target is. Fully self-aware intruders are the hardest of all to affect, followed by unaware intruders and the things they're particularly attached to. To the fully self-aware, everything in the known world is equally easy to affect as long as the desired transformation doesn't directly impinge on anything else from the unseen world.

The characters have bonds to the known world which reflect aspects of their unseen world selves. I'm thinking that some of these should be set by the players, some not, to fold in an element of uncertainty. Bonds are rated on a scale of 1 to something or other to reflect overall intensity. When the subject of a bond is destroyed, the character's overall ability to gain self-awareness is permanently capped. Awakening in such circumstances is possible, but hard. When, on the other hand, the character succeeds in transmuting the bond, then the bond strength raises the character's measure of self-awareness. I'm envisioning the transmutation process as a matter of being able to separate oneself from the subject of a bond for a while - obviously the more significant it is, the more the character's drawn to it. Quite possibly matters like rest and recuperation are harder when one is in the transitional process.

Thus far my thoughts...er, so far.

Sounds pretty sweet.