Procedural techniques will soon automate many aspects of content creation for computer games. We describe an efficient, deterministic, methodology for procedurally generating 3D game content of arbitrary size and complexity. The technique progressively amplifies simple dynamically generated data structures into complex geometry. We use a procedural pipeline with a minimum set of controls at each stage to facilitate authoring. We show two examples from our research. Our terrain generator can synthesize massive 3D terrains in real-time while our level generator can be used to create indoor environments offline or in real-time.