The Blender Game Engine is a component of Blender, a free and open-source comprehensive 3D production suite, used for making real-time interactive content. The game engine was written from scratch in C++ as a mostly independent component, and includes support for features such as Python scripting and OpenAL 3D sound.
Besides the fact of the Open Source and public domain (: . The way blender mix a whole bunch of tools allow us to make everything we want. But the thing I love the most, is for now so basic that maybe no many people thing about that; but the way Blender Render works with BGE its just awesome!
*my bad, for the poor english*