From the back of the book:
It's a novel. It's a game. It's both. It's Castle Falkenstein, an amazing journey into another universe just a few steps away from our own: a place where Dragons and Steampower rule the skies, Faerie Lords duel atop the battlements, and where the forces of Wizardry and Magick meet the gaslight streets of the Victorian Age. But with Castle Falkenstein, the story never ends, as you too take up saber and spell to adventure in a distant world on the other side of the mysterious Faerie Veil: a world of Swashbuckling Fantasy, High Romance, and Magickal Technology.