Castle in 3D

Hi to everybody, for a long time I looked for a software free to realize games open source. I must not create a game but a virtual navigation of a medieval citadel. The objects are created with blender, I have tried UDK too complex and Unity 3d, but don't have the shaders (the free version), instead the blender game engine is too simplified. I hope to succeed us with Maratis. even if I see that it is still to the beginnings as software, but I will try there. I hope to have a support from this comunity. and I hope a lot to a version Livux 64 bits.