Over the past few days I finally started reading Night Watch, the first part of Sergei Lukyanenko’s gritty supernatural tetralogy set in Russia. Without getting too much into it, the concept of Twilight helped me come up with an important element to the cosmology of Catgirl: The Storytelling Game.
The Shadow, also known as the Twilight, the Between, the Divide, and so on, is the immaterial world’s intrusion into and reflection of the material world, and vice versa. It is where the Awakened are at their strongest, because both sides of them are fully expressed. The Shadow looks like an approximation of the material world, but many mental and spiritual factors are plainly manifest. The symbiotic relationship between the two sides of reality allows influences to flow both ways. People can be affected by and exert influence on things in the Shadow, often without realizing it. They can unconsciously shape the Shadow landscape around them, but changes to it can likewise affect them back.
Most Awakened have the power to enter the Shadow, though some individuals are better at it than others, and some don’t even know that they can. Catgirls don’t have any powers that let them exert special influence over the Shadow, but anyone who can enter it can do things that have an effect. If Timmy’s recurring nightmares have formed a monster in the Shadow, defeating it will most likely let the boy sleep soundly at night. For this reason, deftly entering and navigating through the Shadow can be a very powerful skill to have. Some of the most desperate and dangerous battles fought by the Awakened have been fought to control part of the Shadow, and through it exert influence on the other worlds.
For better or for worse, it is unhealthy to stay in the Shadow for extended periods of time. Existing in the physical or spiritual realms naturally saps some of one’s vitality, but existing in a place that comprises both is draining both physically and spiritually at the same time. This is why most awakened only partially immerse themselves into the Shadow. By staying rooted into the material or immaterial worlds while entering the Shadow, it is both less draining and easier to leave if need be. Of course, it does mean truly existing in two realms at once, opening up the possibility that other people will think you’re crazy for reacting to stuff they can’t see. It is possible to enter more fully into the Shadow, but going into the deep Shadow for a length of time will cause those foolhardy enough to do so to waste away and go mad.
It is tempting to think of reality as a Shadow sandwich with material and immaterial bread, but things are not that simple. There are countless peaks, valleys, whorls, and tangles that render the sandwich metaphor untenable. Those who know how to navigate the Shadow can find shortcuts through reality, cutting through one realm to gain ground in another. The variations in this structure and be very broad, or impossibly fine. Sometimes pieces of an immaterial realm can even have a needle-thin breach leading to a specific person.
I also got my copy of Werewolf: The Apocalypse (first edition) in the mail today. I haven’t had a chance to do more than flip through it, but wow. White Wolf has really changed in the 15 years since then. The old logo says “A Renaissance In Gaming(tm)” below it.
Also, does anyone know of anything similar to Night Watch that might be a good source of inspiration?
Yaruki Zero Games 
There’s ‘Night Wizard’, a Japanese-only RPG where monsters called ‘Emulators’ try to enter the world, and Wizards do their best to destroy them. The battles take place in yes, something like what you’re describing. Wiki it. ^_^
The plane of ghosts in White Wolf’s ‘Orpheus’ is something similar, in that Spectres generally only appear on the immaterial level- Unless they can manifest, and if they can, you’re in big trouble. It might be a bit *too* dark, but Orpheus is still an excellent game. I highly recommend the 1st, 2nd and 4th books of the series.
I may have told you this before, but I’d like to recommend two recent SMT games for the PS2: Devil Summoner and Persona 3.
Devil Summoner takes place in an alternate history 1930 japan casts the player as a devil summoning detective. He can see the devils and spirits floating and hiding around the Capitol and he can catch them to solve detective work, but the problem is they can also see him, and will often attack the hero as he’s going from street to street, all the while the general populous is unaware.
Persona 3 is of note due to the “hidden hour” just after midnight. Every full moon, creatures called shadows wreak havoc during the dark hour where normal people turn into coffins. The heroes can use “Personas”, spirit representations of their psyche, to fight the shadows, however they discover that their power is also tied to the dark hour.
The twist is that if they knock off the main shadows who control the dark hour and appear every full moon, their persona powers will go away as well.
…And the end of the world will happen. Nothing surprising, considering how *every* Persona game involves the end of the world, at one point or another.
The end of the world occurring in a Japanese RPG? What are the odds?
I brought up the last part as it brings up a good question that the heroes must answer: “If you had a super power, that made you important, would you get rid of it and be a nobody again if it meant ridding the world of a terrible evil?”. I haven’t really seen that brought up in a lot of stories in that manner…
There’s a comic, the Sentry, that addresses exactly this. Every time the Sentry comes into existence, so does his nemesis, the Void. However, when the Void is destroyed, everyone, even the Sentry himself, forgets about it…
Of course, he was retconned in a square-jawed hero, instead of the half-delusional wreck he was in his first series.