In a computer-implemented method of generating a virtual 3D environment, a hierarchy of slots is provided. The slots are organized in tiers from one or more top tier slots to one or more bottom tier slots. Each slot defines a portion of a 3D environment and includes a plurality of layouts. Each layout of a non-bottom tier slot defines a position of at least one slot from a lower tier within the portion of the 3D environment. One or more of the top tier slots are positioned within the 3D environment. The 3D environment is generated by randomly selecting one of the plurality of layouts of the top tier slot and the lower tier slots, and populating each of the selected layouts with one or more objects. The 3D environment is rendered for display.