Game Cheat Engine

3D game engine (more powerful redesign of the Cube engine) and FPS game Platforms: Windows, Mac, BSD, Linux

A moddable 2d platformer/side-scroller game engine. Due to the dynamism and abilities of Python all elements of the engine may be subclassed and extended to provide unlimited functionality to the developer. Platforms: Windows, Mac, Linux

The Freya Game Engine is a cross platform Java API for writing multiplayer turn based games. The engine produces XML turn descriptions based on XML command files and XML data dictionaries. Platforms: Windows, Mac, Linux

GemRB (Game engine made with pre-Rendered Background) is a portable open-source implementation of Bioware's Infinity Engine. It was written to support pseudo-3D role playing games based on the Dungeons & Dragons ruleset (Baldur's Gate and Icewind Dale series, Planescape: Torment). It should run... Platforms: Windows, Mac, BSD, Linux

The General Adventure Game Engine is a generic RPGAdventure game engine written in C++. Platforms: Windows, Mac, Linux

A universal 3D game engine designed to be portable, powerful, flexible, and easily extendable through an extensive plugin system. Platforms: Windows, Mac, Linux

A very high level 2d tile grid based game engine written in Python and PyGame. It is intended to make programming 2d tile grid based games much easier, especially for novices, while retaining the flexibility required by more experienced programmers. Platforms: Windows, Mac, Linux

The MAD Project is an attempt to create a powerful, flexible game engine, which is specifically designed for graphical adventure games. Platforms: Windows, Mac, Linux

Orx is a portable, lightweight, plugin-based, data-driven and extremely easy to use 2D-oriented game engine. As orx is data driven, it allows users to create games with a small number of lines of code and reduces drastically the development time. Platforms: Windows, Mac, Linux

PaulRPG: A free role playing game engine, to enable people to create free 'Final Fantasy' style games. The data file formats are reasonably cross-platform supportable, they would just need an interpreter for the different platforms. Platforms: Windows, Mac, Linux

Pipmak is a cross-platform game engine and authoring environment for point-and-click adventure games in the style of the Myst series. It supports panoramic nodes and uses Lua for scripting. Platforms: Windows, Mac, BSD, Linux

Pyzzle is a cross-platform game engine for creating large-scale, 2D Myst-like adventure games. The engine supports 2D panoramas, features an intuitive design mode, and allows users to download content from the internet. Pyzzle is written using Pygame. Platforms: Windows, Mac, BSD, Linux

The first 3D game engine built in C# for .NET, predecessor to the Visual3D Game Engine (http://www.visual3d.net/game-engine), an All-in-One Game Development Tool for Next-Gen 3D Games, MMOs, Simulations and Virtual Worlds powered by Microsoft XNA. Platforms: Windows, Mac, Linux

A mutiplayer scriptable game engine written in Common Lisp.Designed for experimenting with AI and scriptable control systems.The game is combination of a graphical nethack and space shooter. Platforms: Mac, BSD, Linux

Spineless is a generic cross-platform 3D game engine implemented in Python. Focus is on flexibility, clean design and ease of use, not pure speed or bleeding edge graphics. Platforms: Windows, Mac, Linux

Game & Watch Simulator is a generic engine for simulation of Game & Watch-like games. It is designed to run anywhere SDL is available, with emphasis in handheld machines. In case of Madrigal simulators, the simulation is aimed to be as close as possible to the real machine, simulating on-off, ACL... Platforms: Windows, Mac, *nix, C/C++, BSD Solaris

Web-Based Role Playing Engine (for Web Game RPG). Client implemented with Javascript, Ajax, DOM and DHTML. On server, PHP and database (FireBird or MySQL). Ajax is used to communicate client to server. Platforms: Windows, Mac, *nix, PHP, BSD Solaris

Php Stategy Game Engine (phpSGE) is an open tool for creating a php strategy browsergame that you can customize.PHPsge is very easy to use and it has a simple administration panel (for editing the game), and auto istaller.You can easy canghe the style of your game changing the css (that you can... Platforms: PHP

Amoeba RPG engine is an rpg engine in the style of early Final Fantasy games. It will be implemented in Mozilla (xul,js) and based upon a game xml language. Platforms: Windows, Mac, Linux

judge - an OO mud (multi user dungeon) engine based on a client/server architecture and written entirely in java. This d20 based game engine will eventually make use of JINI to allow certain functions to be performed locally or by other dedicated servers Platforms: Windows, Mac, Linux