Demon: The Descent
The very first gameline created explicitly for the 2nd edition of the New World of Darkness. It abandons the explicitly Christian themes of Demon: The Fallen for a much more unique setting of "techgnostic espionage".
See, the World of Darkness has a thing in it called the God-Machine. A mechanical demiurge - a computer so vast and powerful that cities are part of its hardware and the laws of physics the results of its software. This God-Machine is so powerful that it can create sentient quantum reality computer programs, called Angels. And sometimes, these Angels get corrupted. Usually, by starting to take an interest in humanity and the physical world around them. These Angels gain their free will and Fall, burning out their connections to the God-Machine and becoming independent entities, called Demons.
The end result is awesome; spy-thriller themes against a religious horror meets mad science verneer.
The first gameline in the NWoD to completely abandon Morality; instead, Demons have Cover, which is how well they stay in character for their human guises. There's nothing mentally wrong with burning a Cover out... but it does make you an easy target for the God Machine...
Demons are defined by their Incarnation (what they were created for; Destroyers, Guardians, Messengers and Psychopomps) and the Agenda (what they seek to do; Inquisitors hunt for knowledge, Saboteurs want to destroy the God-Machine, Temptors want to indulge in mortal pleasures, and Integrators want to find a way to go back to the God-Machine on their own terms). They can actually belong to two Agendas at once, as well.