Game engines are software frameworks for game development. Game engines do the heavy lifting for developers so they can focus on other aspects of game development.
The ioquake3 community effort to continue supporting/developing id's Quake III Arena
UPBGE, the best integrated game engine in Blender
Awesome list of resources for Game Engine Development.
Lina Engine is an open-source , modular, tiny and fast C++ game engine, aimed to develop 3D desktop games.
A Cool High Performance Game Engine
Archived repository. For current repo, see: https://github.com/etlegacy/etlegacy
FMOD Studio middleware integration and scripting API bindings for the Godot game engine.
Go 3D and 2D game engine using Vulkan (https://kaijuengine.org)
Game Engine Development Series - Learn to code a Game Engine in C++ from scratch
Android Memory Access at Runtime: Reading and Writing Using Memory Files and Maps
Personal repo for learning the vulkan graphics api
2D RPG Game creator
Lightweight Sandbox Game Engine using OpenGL for additional Customisation and Quick Prototyping
Open source recreation of original Sonic The Hedgehog 1991 game on C++ programming language.
C++ OpenGL game development engine for Windows and Linux.
Code accompanying the Medium article "Dependency Injection for Games"
📚 Java Game Engine for text-based games.
Prototyping turn based card game
Initial steps into game engine development
TypeScript based 3D game engine.