g3nd is the official demo/showcase application for the g3n Go 3D game engine. It is a single Go binary that presents a windowed GUI (built on the engine's own immediate-mode GUI system) with a categorized demo tree. Users select demos that exercise the engine's capabilities: glTF/glb loading, PBR materials, animations (skinning, morph targets), audio (OpenAL), particle systems, post-processing shaders, and GUI widgets (tables, trees, sliders, form boxes, dock layouts). The application registers demos via Go's `init()` side-effect pattern: each demo package imports itself and calls `app.DemoMap["category.name"] = &struct{}{}`. The core `App` struct manages the scene graph, camera, orbit controls, and per-frame `Update` dispatch. The repository also vendors a large set of test assets (glTF sample models, Blender files, audio, textures) under `data/`. The architecture is a classic Go application: `main.go` imports all demo packages for their registration side effects, then delegates to `app.Create().Run()`. The `app` package owns the window, GUI, and demo lifecycle. Each demo implements a minimal `IDemo` interface (`Start`, `Update`, `Cleanup`). The `util` package provides reusable GUI helpers (file selectors, light meshes). The demos are grouped by category: animation, audio, experimental physics, geometry, GUI, light, loader, material, other, shader, texture. The code is idiomatic Go with clean separation, but some demos are marked experimental and the engine dependency is a pseudo-version that may drift.