An isometric arcade-style game of skill, puzzles and exploration
SDL based generic 2D game engine
PyCAPGE - Python Classic Adventure Point and Click Game Engine
Open-source, cross-platform, C++ game engine for creating 2D/3D games
An advanced flexible game engine for Java.
Cross-platform C framework very compact libraries and tools.
An extensible development framework for roleplay games.
Open Source Virtual World and MMOG Development Platform
Zap Engine