lua dev plugin for unreal engine 4 or 5
Godot game template and component-based framework
3D game engine/framework in C, with Luajit and Python bindings now
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
A cross platform Lua based game engine
3D-Accelerated open-source DOOM engine
EDGE is an advanced DOOM source port
starrydb is game server engine
A free engine for C&C Tiberian Dawn
Pear3DEngine is a modern and modular 3D development framework
Make games with Lego-like building blocks