Keystone — Building Generator (Unreal Engine Plugin)
Every building, from one idea.Keystone generates game-ready 3D buildings — walls, floors, roofs, and approximate interiors — directly in the Unreal Editor. Start from a preset, draw a footprint, drop a floor-plan image, or describe a building in plain English. Keystone builds it, and bakes it to Nanite static meshes with collision that you own outright.No subscription. No credits. No AI-generated meshes. Just a fast, deterministic building generator that meets your idea wherever it already lives.Five ways to start a building Presets — eight starter buildings, one click each: House, L-Shape, Gable Cottage, 3-Storey Block, Setback Tower, Castle, Log Cabin, Round Tower. Sketch — draw the footprint on a true-to-scale 2D canvas (snapping, ortho, real Unreal units). Place doors, windows, and interior walls as you go. Floor-plan image — load a floor plan and turn it into a building, with an alignment/correction overlay so it matches your scale. (Uses your own AI key — see below.) Text — describe a building ("two-storey stone cottage, hip roof, door and three windows") and draft the massing instantly. (Your key.) Your own meshes (Kit Mode) — tile your log / brick / stone / sci-fi modular meshes onto walls and floors, with correct placement and pivots. Bring your own kit, marketplace packs, or Quixel/Megascans. Built for real projects Game-ready output — bakes to Nanite static meshes with collision, as separable pieces (each wall, roof panel, floor) you can edit, swap, or detach. Multi-volume composition — compose castles, towers, gatehouses, and wings — not just single boxes. Architectural character — stacked-log and timber wall styles, cornices and crenellations (detail bands), arcs and round towers, and subtle "stylize" deformation for hand-made variation. Deterministic and tested — the same input always produces the same building. A refinement pass repairs raw AI output before geometry is built. The deterministic geometry core is validated by a 56-test automation suite in development. Round-trip your designs — import/export the building file (JSON) to version, share, and iterate. Own it. No meter. One-time purchase. Lifetime updates. No subscription, no credits, no usage fees. Bring your own AI key for the text and floor-plan features — Anthropic, OpenAI, or Google — or run it fully local with Ollama. Your inputs go only to the provider you choose; nothing is sent to us, and no AI-generated meshes are shipped or sold. The entire preset / sketch / Kit-Mode / parametric workflow works with no AI at all. Who it's for Indie devs filling worlds with varied, game-ready buildings without hand-modeling every one. Archviz artists turning client floor plans into Unreal buildings, fast. Students and hobbyists who want to go from an idea to a building in minutes. Virtual-production and previs teams dressing backgrounds at scale. A note on interiors: Keystone drafts approximate interiors (floors, ceilings, interior walls, openings) — ideal for blockout, exteriors, and mid-ground buildings. We'd rather tell you exactly what it does than oversell it.Try it free: Keystone Lite is a free version with presets, the 2D sketch canvas, and Nanite baking. Upgrade to the full Keystone for AI input, multi-volume castles/towers, Kit Mode, and the full detailing toolkit.Requirements & dependencies Engine versions: UE 5.3, 5.4, 5.5, 5.6, 5.7, 5.8 — a separate, compile-verified build per version (download the one matching your engine). Platform: Windows (Win64). It is an editor-time tool; the buildings it bakes are standard StaticMeshes usable on any target platform. Engine plugin (required, auto-enabled): Keystone uses Unreal's built-in Geometry Scripting plugin to generate the building meshes and bake them to Nanite-ready Static Meshes. It ships with Unreal (no extra purchase) and is enabled automatically with Keystone. No other plugin is required. Optional AI features (Draft from Text / Draft from Image) require your own API key (Anthropic / OpenAI / Google) or a local Ollama install. Every non-AI workflow works without them. No dependency on any other third-party or user-made plugin. Created with AI (disclosure)Keystone's 3D geometry is generated by a deterministic procedural engine — not by generative AI. Two optional features (Draft from Text, Draft from Image) use a large language model only to interpret your text or floor-plan into editable build parameters, and only when you supply your own API key (Anthropic / OpenAI / Google) or run a local model (Ollama). No AI inference runs without your key, no buyer data is sent anywhere except your chosen provider, and no AI-generated meshes or assets are included in this product. Some of the plugin's source code and this listing's marketing materials were produced with AI assistance.Support Support: https://mythiclemon.com Documentation: User Guide + Technical Reference PDFs included with the download. Built and maintained by MythicLemon.
Get it → mythiclemon.gumroad.com