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.
Kaiju Engine - Multiplatform 2D and 3D Vulkan game engine written in Go/Golang
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.
📚 Java Game Engine for text-based games.
Code accompanying the Medium article "Dependency Injection for Games"
Prototyping turn based card game
Initial steps into game engine development
TypeScript based 3D game engine.