Are there any game / graphics engines for the D programming language?
Most likely, there are quite a lot of infact (albeit at different stages of maturity). Check out the game section on dsource: http://www.dsource.org/projects/
You can check DAllegro and DAllegroGL . They are mainly in C / C ++, but contain a D language binding.
there are ports for the horde3D engine, they can be found on the forum: horde 3d homepage