Free Engines
Agar (engine) - A high-level graphical application framework used by 2D and 3D computer games
Allegro library - A free crossplatform C/C++ game programming library, provides functions for graphics, sounds, input, timers, fixed and floating point, 3d, compressed datafile and a GUI.
Axiom Engine - A fork containing the core of the OGRE graphics engine
Haaf's Game Engine - A 2D Hardware Accelerated Game Engine
Baja Engine - Professional quality engine used for the game The Lost Mansion.
Boom - A port of the Doom source code by TeamTNT
Build engine - A First person shooter engine used to power Duke Nukem 3D
Cadabra 3D Engine - 3D engine for easy game development
Catmother - A BSD-licensed engine from a company that open-sourced its code when it closed the business.
CheapHack - An outdated TomazQuake derived engine
Crystal Entity Layer - An extension of the Crystal Space 3D Engine
Crystal Space - A general framework for developing 3D applications
Cube - Powers the computer game of the same name
DarkPlaces - One of the most advanced free software Quake engines
Delta3d - Integrates other well-known free software projects into an easy-to-use API, originally developed by the U.S. Navy
DGD - An object-oriented programmable MUD engine
Doom engine - The now free software engine originally used for Doom and Doom II
DXFramework - A simple, pedagogical 2D/3D DirectX-based game engine for Visual Studio
DX Studio - Real-time professional 3D engine and editing suite produced by Worldweaver Ltd
Eclipse - A 2D MMORPG maker (Open source)
Elysium Source - A 2D online game engine made with VB6
Epee Engine -Is an 2D/3D open source cross platform graphics engine with beginning programmers in mind
Eternity Engine - A source port of the Doom engine
Exult - A free software reimplementation of the Ultima VII game engine
FIFE - A free software 2D ISO engine supporting the assets of Fallout 1 & 2
Game Blender - A sub-application of Blender for creating games
Game Maker - Object-oriented game development software with drag-and-drop interface and its own scripting language
GQ - A Quake engine that adds features from TomazQuake and DarkPlaces
GZDoom - A source port of the Doom engine based on ZDoom
Genesis3D - A real-time 3D engine for Windows
GemRB - A free software implementation of the Infinity Engine
Irrlicht Engine - A cross-platform and lightweight three dimensional graphics engine.
Jogre - a Java based client/server game engine and API for online real time games such as chess, checkers, etc.
MRPGe - Visual Basic 2D RPG game engine, with built-in scripting capabilities. Very customizable, in early development stages.
M.U.G.E.N - A 2D fighting game engine
Multiverse Network - an MMOG platform, including server, client, and tools. (Free for development and use--revenue sharing upon commercial deployment).
Nebula Device - A realtime 3D game engine developed by German game studio Radon Labs.
OctLight - A Java game engine that uses scene-graph and renders on top of Lightweight Java Game Library (LWJGL) using OpenGL
Open Game Engine is an open source library combining the components used to make games.
OGRE Engine - A very popular object-oriented graphics rendering engine. Also called OGRE3D
Online RPG Maker - An Online RPG/2D engine with scripting.
Panda3D Engine - Rapid development engine based on Python
Pentagram - A project to create a game engine that is capable of running Ultima VIII: Pagan
PlayerWorlds - a simple, and widely used 2D Online RPG Engine.
PLIB - A game engine - includes 3D, Audio, Music, GUI, Window manager and is portable Linux/Windows/MacOSX.
ProQuake - A modified Quake engine
Quake II engine - The original free software Quake II engine from Id Software
Quake III engine - The original free software Quake III engine from Id Software
Reality Factory - A free open-source game engine that is intended for non-programmers and is built on the Genesis3d Graphic Engine.
RealmForge - An open-source game engine for the Microsoft .NET Framework, predecessor to Visual3D.NET
Sauerbraten - A upgraded engine forked from the Cube engine
Sonic Robo Blast 2 - A heavily modified Doom Legacy engine for a 3D platform fan-fiction game of the same name.
Stratagus - A cross-platform real time strategy game engine
Telejano - a modified Quake engine
Tenebrae - One of many Quake engine clones
Toi - A 3d game engine currently in development with promises of both MMO and single player capabilities. Free but with licensing fees that are to be announced. Has much potential.
vbGORE - Open-source online RPG engine in Visual Basic 6 (2d via 3d hybrid engine).
Well of Souls - A 2D engine with scripting in QUEST and a visual world editor.
Yake - a component-based, object-oriented, partially generic engine written in C++
Zak Engine - An easy to use 2D games engine using DirectX 8.1 and 9 developed for novice and professional programmers. Features: sprites, tiles maps, sound and music in several formats, scripting (AngelScript), particle systems and more!
List of free/open source 3d game engines
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