The year is 1945. Lamenting the boundless wickedness of mankind, God has decided to destroy his creation in its entirety and start anew. To this end, he sends an army of angels to Earth. Equipped with holy weapons of terrible power, the angelic army razes entire cities. No country is safe from their wrath. Happy to see humanity finally get its comeuppance, the demons of hell decide to reconcile with God and join the fight on the side on the angels. Faced with a merciless army of angels and demons, the Axis and the Allies hesitantly forge an unholy alliance of their own. The only way to kill an angel or a demon is to eats its heart and in doing so consume its power. The new human alliance fields an elite unit capable of doing just that. Powered by the hearts of angels and demons, they are humanity's only hope. In the midst of battle, forbidden romance blooms between once-bitter enemies. But the unforgivable transgressions of the recent past weigh heavily on their fragile bonds. And in the darkest reaches of space, an alien force watches with amusement, waiting for the perfect moment to spring its own trap.
Modifications to SR4 rules:
Weapons and Gear - All weapons and gear are replaced with 1945 equivalents. This is mostly a fluff alteration, but equipment that couldn't exist in 1945 does not exist in the game. This means no smartlink contacts, among other things.
Cyberware and Bioware - Cyberware and bioware are replaced with Angel grafts and Demon grafts respectively. They behave exactly like cyberware and bioware (angels are, apparently, cyborgs) and cost Essence. Grafts are, of course, taken from the dismembered bodies of slain angels and demons. Each piece of 'ware in the BBB has an equivilant graft.
Edge - is now a supernatural fuel reserve. Edge spends itself automatically at a rate depending on Essence (I'm thinking 1 point spent per Essence * 4 hours, round up). Edge can only be replenished by eating the heart of an angel or a demon. Each heart eaten refreshes one point of Edge. If a character's Edge is reduced to 0, all of his grafts deactivate and, if a magician or an adept, he is no longer able to use spells or powers. In addition to the standard uses of Edge, a character can spend all of his remaining Edge to perform a desperation attack (Rolling Edge alone and resisted with Willpower, base DV = remaining Edge) on every enemy within his line of sight. A character can have an Edge reserve up to twice his Edge Attribute.
Angels and Demons - Angels and demons come in all shapes and sizes. Most are corporeal beings with the Astral Perception power. Some are dual natured, some exist purely on Astral, and some of the most powerful have totally separate physical and astral bodies, both of which must be destroyed. Angels and demons have the Regeneration Power on both planes and cannot be killed by conventional attacks. If knocked into overflow they will remain unconscious until their Regeneration power heals their wounds or their hearts are cut out, at which point they stop regenerating. Angels and Demons only die if their hearts are eaten by a sentient being. If their hearts are destroy any other way, or returned to their bodies, they will immediately and fully regenerate. Some can cast spells and some can summon spirits.
Spirits - Spirits cannot materialize and magicians who allow themselves to be possessed lose all control over the spirit during the period of possession.
Hackers - No hackers.
Technomancers - I'm not sure. I'd like a way to adapt them but I can't think of any smooth way to do so. Suggestions are welcome.
Hitler is still in power, but has publicly apologized for the holocaust and its role in bringing the Wrath of God down on the world, though the Third Reich still holds heavy nationalist and anti-semitic views. Truman has, likewise, admitted that using nuclear weapons on Japan was a mistake. Japan's leaders were somewhat reluctant to mention comfort women and the Rape of Nanking, but Hriohito made vague apologies for "excesses" committed during the war.
Of course, the human alliance happily commits similar excesses against the supernatural forces rallied against them and their human devotees, with little hesitation and the armies of heaven and hell commit similar atrocities without even the slightest bit of reluctance or remorse.
PCs are Axis and Allied soldiers, now joined together for a common good, imbued with magical powers stolen from the enemy. Some are monstrous hybrids possessing limbs and organs from taken from dismembered enemies. Others were well-versed in the occult before the war took its strange turn and are able to manipulate the eldrich forces of the universe with the help of stolen angelic and demonic power. Their missions include various covert actions behind enemy lines, ranging from kidnapping and rescue to theft to information gathering to assasination to terrorism to outright open combat.
Most enemies are human zealots with more religious faith than common sense, some transformed into paracritters by their masters while the lowest tiers of angels and of demons are not much more powerful than human zealots they are rarer.