Covenant: Hellgate: London 3: London v. 3 (Hellgate London 3)

Novelisation of a stunning new computer game.
London, 2038.
Man became dependent on science, believed only what he could define or create. Ancient knowledge and rituals were lost. Prophecies ignored. So when the harbingers of evil began to manifest, few saw and fewer believed.
So when the demons came there was little to stand in their way.
Emerging from the swirling chaotic Hellgate, they overwhelmed humanity's defenses. The usual tactics of war were useless were useless against them - only the few who still respected the old ways, with their holy, ancient, and arcane rights could stand against the dark invaders, using weapons and spells forged in the traditions of their forefathers. But their scattered sucesses attracted vastly powerful enemies, forcing the survivors of London deep into the relative saftey of the Underground.
Above them London lies in ruins. A massive, sinister gash in the fabric of reality swirls and churns, dominating the horizon as it blends into a permanently darkened sky. The Burn - transforming our world into theirs - began, while the remnants of our civilsation hid.
But mankind is a race of survivors. Men and women hide in the shadows of their former world, struggling to survive, yearning to strike back at their conquerors. They are banding together, and they are learning.
Learning how to travel undetected.
Learning how to forge effective weapons.
Learning how to harness the forgotten power of magic, and fuse it with science.
Learning how to kill demons, and close the Hellgate . . .