This is simply amazing. Someone that goes only by the name of Voxel, has created a 3D version of the original Metroid game in Director, titled Metroid Cubed! By taking the Metroid tileset, he built a utility that allows him to convert 2D sprites to 3D sprites, and then he uses those to build the levels of the game. Check out his site, which also has a complete history about how and why he did what he did.
Play Metroid Cubed (requires Shockwave).