From publisher blurb: “Just after dawn, a village scout dashed from the forest carrying a wondrous, and perhaps even terrifying, story of a huge, circular shell with a door, a massive coiled building that sprang up during the night. And it is still growing … ” Whether from forgetfulness, mental blockage, or intrusions of the dread “real life,” every storyteller has probably experienced that sinking, not-so-prepared feeling before a game. This sourcebook provides a remedy for the next time that happens, and includes an adventure location that is both a little pre-generated and a little homemade, is immediately expandable and adaptable, and can be replayed without seeming like a re-run, because the building changes even as the characters explore it. “The Living Building” includes background and physical description for the title structure; a floorplan for a particular living building; problems with living buildings that can make them interesting and dangerous places to explore; tips on using living buildings in game sessions; tables for determining the contents of rooms; hazards that characters might face in living buildings; and a section on monsters particularly likely to be encountered in living buildings that includes four new creatures and three new mutations. Material in this publication was written specifically for the Mutant Future retroclone of Gamma World and can be used as-is with it and any other sci-fi, fantasy, or post-apocalyptic games that use the "Basic" version of the OGL system, and easily adapted to other games using the same core rules. It was written by noted game developer Derek Holland and includes cartography by artist William T. Thrasher.