A free, open source game engine written in C++ that's modular and flexible, such that it can be adapted to many different use cases.

an open-source 3d game engine written in C++, it has powered several successful commercial titles across various platforms including Steam, PSN, iOS, and the Mac Store.

Pragma is a free, open source custom game engine written in C++

An open source C++ toolkit for creative coding.

ENIGMA is a free development environment geared towards game development and compatible with Game Maker projects

Game engine behind Sea Dogs, Pirates of the Caribbean and Age of Pirates games

A 2D game development library for Ruby and C++, with few dependencies and great to learn Ruby or for short game development competitions

SnaX is a fast and lightweight development tool for 3D-graphics applications based on a real-time, visual programming concept

Battle tested game engine with visual scripting for 3D games

Urho3D is a free lightweight, cross-platform 2D and 3D game engine

Software library and tools for making the Tramway Drifting and Dungeon Exploration Simulator 2022 and similar applications. Similar to Quake, GoldSrc or Source engines, but it uses polygonal soup instead of BSPs and supports level streaming.

A powerful game development platform to create world-class entertainment experiences

The Irrlicht Engine is an open source realtime 3D engine written in C++

nCine is a cross-platform 2D game framework written in C++ with an emphasis on performance, but it is also scriptable in Lua for more flexibility. You can use it to create your games and tools or to learn and experiment with its source code.

Lost Astronaut's Game Creation Framework: A massive 1800+ class 1400 file extravaganza of OpenGL, WinAPI, OpenAL and many other features, written in Visual Studio for over a decade! The project seeks to port to a Linux/Winux environment from Visual Studio.

And engine to make simulations of any kind, ranging from simple prototypes to professional 2D and 3D games, simple physics or graphics demonstrations to robust, realistic simulations

Echo is a game engine which uses many industry-standards for game development

2D Game Engine with Lua Scripting made on top of SFML

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

A cross platform game engine that can be used to make simulations of any kind, ranging from simple prototypes to professional 2D and 3D games, simple physics or graphics demonstrations to robust, realistic simulations.

Limon is a multi platform 3D game engine mainly focusing on first person games. Focus of its development is ease of use and ease of study.

The successor version of Kirikiri 2, allows you to create 2D games and applications, and is used in many commercial adventure/novel games

Dark Basic Pro is an open source BASIC programming language for creating Windows applications and games

A 3D game engine created by Valve in 2004, and has been used by Valve, third-party companies, and countless community mods by people around the globe

A complete 3D authoring tool which includes all the features you need for creating games for multiple platforms

A free, all-in-one platform for game creators

C++ Coding Framework for Windows, Linux, macOS and Browser games

"Esenthel" is a mix of words: Essential and Essence, with a touch of magic

A small, 3D game engine/framework in C, with Luajit and Python bindings

3D Real Time engine and visualization tools for the Industry, scientists & education.