Lumix Engine
3D C++ Game Engine - yet another open source game engine
...It features a modern, component-based design (entity-component-system) and offers a full editor — enabling developers to build games in a WYSIWYG style similar to engines like Unity, while staying in a lightweight, open environment. The engine supports advanced rendering (with PBR, HDR, deferred rendering), physics, audio, animation, scripting (via Lua or even JavaScript via plugin), and more, giving it a robust feature set for realistic 3D games or simulations. Users appreciate that much of the engine — rendering, assets, scripting, editor — can be hot-reloaded, which greatly speeds up iteration. It runs on Windows and Linux, is MIT-licensed, and is backed by a community that provides documentation, demos, and examples (such as a demo platformer).