Discover the secret history of the war that may (or may not) have happened: a time of strangely enhanced soldiers, more machine than man; a twisted future-past of occult and technological development and intrigue; and a society where humanity struggles to maintain its increasingly fragile grip on reality. Featuring a variant, Mythos-fueled history for the Interface 2.0: Full Metal Cyberpunk setting, where ancient gods watch your every move from the shadows of the datastream, Interface 19.40 introduces new rules on how to include cyberware, gruesome genetic manipulations, and even weirder science in your Achtung! Cthulhu games, plus a whole Crossover dossiers worth of useful Alternate Historical and fantastical information to help you expand your campaign out into the wider world of the Secret War.