FIFE is a free, open-source cross-platform game engine. It features hardware-accelerated 2D graphics, integrated GUI, audio support, lighting, map editor supporting top-down and isometric maps, pathfinding, virtual filesystem and more!
The core is written in C++ which means that it is highly portable. FIFE currently supports Windows, Linux and Mac.
Games utilizing FIFE are programmed through Python scripting layer on top of the base C++ API. Games can be also programmed using the C++ layer directly.
FIFE is open-sourced under the terms of the LGPL license so you can freely use it in non-commercial and commercial projects.