A fully featured, open source, MIT licensed, game engine. [MIT]

A simple and easy-to-use library to enjoy videogames programming. [zlib/libpng] website

Gaming meets modern C++. [MIT]

An open-source, real-time, multi-platform 3D engine based on Amazon Lumberyard. [Apache2] website

A game engine, a framework for 3D rendering and game development for Python and C++ programs. [Modified BSD] website

A cross-platform native C++ game framework for creating 2D/3D mobile and desktop games. [Apache2]

The official distribution of olcPixelGameEngine, a tool used in javidx9's YouTube videos and projects. [OLC3]

A lightweight game engine written in C++14 with a "true" entity-component system. [Apache 2.0]

A powerful free cross-platform RTS game engine. [GPLv2/GPLv3] website

a community-modified X-Ray engine used in S.T.A.L.K.E.R. game series. [Modified BSD/non-commercial only]

A cross-platform framework for creative code in C++ (with Lua bindings). [MIT] website

a cross-platform open source game engine with plugin-based architecture. [GPLv2] website

A game engine written in pure C, SDL and OpenGL. [BSD]

toy is a thin and modular c++ game engine and offers simple expressive c++ idioms to design full featured 2D or 3D games in fast iterations.

An open-source C++ engine built for 3D game development. [MIT] website

Is a free, open-source game engine written in C++. Its philosophy is to be modular and flexible, such that it can be adapted to many different use cases. [MIT] website

An open-source and cross-platform C++ engine built for 2D game development. [MIT] website

A cross-platform 2D game engine with an emphasis on performance, written in C++11 and optionally scriptable in Lua. [MIT] website

A cross-platform game engine for desktop, mobile, and XBOX (UWP), derived from Cocos2d-x-4.0. [MIT] website

2D library for Linux, Windows, macOS, Android, iOS, Xbox, the Nintendo Switch and the Web. [zlib] website

Community project to build a free game engine for implementing open world 3D games. [MIT]

Actively maintained branch of the original Quake engine code with 20+ years of development. [GPL-2.0]

A cross-platform library mainly aimed for video games and multimedia programming. [zlib]

A multi-platform framework for building 2d games, interactive books, demos and other graphical applications. [MIT]

Crown is a general purpose data-driven game engine, written from scratch in orthodox C++ with a minimalistic and data-oriented design philosophy in mind. [MIT]

A robust simulation platform. [LGPL2]

A cross-platform 2D C++ game engine. [MIT]

A free lightweight, cross-platform 2D and 3D game engine implemented in C++. Greatly inspired by OGRE and Horde3D. [MIT]