A basic 3D environment with a first-person POV
3D Game engine
Small OpenGL based game enegine
Visual Novel engine, editor and game development.
TR Game Engine allows you to develop your game quickly and easily.
Distributed game engine
A retro style video game engine for RPGs and adventure games.
2D Game Engine, based on OpenGL and focused on Isometric Games
3D game engine for C and C++
A 2D java game engine
Smokin' Guns - unofficial release for Mac OS 10.5
Tactical, turn-based game engine, that uses OpenGL and WinAPI
Summer 2013 Collab
C# 2D Game Engine - Work In Progress
Java Client + JS/Canvas Server-Side System, with maintained Objects
WGFX 2D Game Engine
Javascript adventure game engine
Scripting language of the hawk game engine
RTS engine