Installation

In Blender open Edit, Preferences, Get Extensions, then use Install from Disk and pick the ruins_generator zip.

Ruinify a building

1. Select your building (any mesh) and open the Ruins tab in the 3D viewport sidebar (N).
2. Press Ruinify. The top breaks, holes open, the glass goes and rubble, moss and ivy appear.
3. Change Decay, Holes, Rubble, Moss, Ivy and Grass, or press New Collapse for another seed. Everything updates live.
4. Apply bakes the ruin into the mesh (rubble and plants stay as separate objects); Remove gives the original building back.

Build a ruin

1. With nothing selected, click the big picture in the Ruins tab to browse the 31 ruins, then press Add. You can also use Shift+A, Mesh, Ruins.
2. With a ruin selected, its card shows the picture (click it to switch to another ruin), the height and the face count, plus Surprise Me, Variation and New Collapse.
3. Decay and Nature hold the main sliders; Shape, More Damage, More Plants, Ground and Finish hold the rest (size, height, columns, arch style, block size, climate, roots, vines, stone and trim materials, tint and grime).
4. Convert to Mesh turns the ruin into plain meshes for export; Delete removes it with all its parts.

All sizes are in meters. Use the Low detail level for distant views and games, High for close-ups.