Agar - A graphical game engine aimed primarily at applications ranging from SDL 2D games to multithreaded 3D simulations. The engine currently implements tile-based levels, a level editor, a GUI, and various other interfaces for game programming. [Open source, BSD License]
Betatron - For the creation of 2D-platform and action-arcade games in C++ for the DJGPP v2.0 compiler. [Open Source]
ClanLib - A multi-platform game development library. Currently is works on Linux and Win32. [Open source, LGPL]
Clean Game Library - A complete development system for 2D games (arcade, side scrollers, platform games), using the functional language Clean.
DimensioneX Multiplayer Adventure Development Kit - Offers a freeware Java software capable of building and running multiplayer adventure games, playable with any browser. Several multiplayer games are available for free as a demo.
GapiDraw - A complete toolkit to create games for handheld devices. [Free for non-comercial use]
The Grand Unified Toolkit (GUT) - A cross-platform C++ API for the development of games and other forms of interactive media. It is available for the BeOS, Linux/X, and Win32 platforms.
Hyperion Project - Set of components which handle the deformation of solids in real time. Special FEM adaptation.
ika - A Windows based game engine designed to allow one to make a console style RPG with a minimum of code, while allowing one who is willing to code an impressive level of power over the look and feel of one's project, thanks to the embedded Python interpreter. [Open source, GPL]
IsoEngine - A Visual Basic/C++/.NET isometric/2d game engine. [Commercial]
Jet3D - A (commercial) free and open source realtime 3D graphics engine and SDK.
MIDAS Digital Audio System - MIDAS is a multichannel digital sound system. It supports DOS, Win32, and Linux platforms and plays Protracker (.mod), Scream Tracker 3 (.s3m), FastTracker 2 (.xm) and Impulse Tracker (.it) modules, as well as samples and audio streams in raw or WAVE . MIDAS is free for non-commercial usage.
MoleStudio SpriteCraft - An easy-to-use 2D game engine. It can be used in any programming language suppoting COM.
PathLib - Pathfinding library for games, optimal paths through maps, timing objects and their movements through maps. Sample application available.
The Photon Effect - libCON DirectX C++ libraries and ColDet collision detection libraries. Documentation, tools, code examples, and game skeletons available.
RAD Gametools - Develops game software technologies which are licensed by primarily by video game companies.
RakNet - A game orientated networking API that is a wrapper for Berkely Sockets on Windows, Linux, and Unix. [Commercial]
