I think this is something abouit having transparent textures on the game. to have them transparent you need to have 'alpha blending' supported.
Im not really too sure, but I know that transparency on a .png image is sometimes called alpha blending. example, you could say that you need a program that supports alpha blending, to make a semitransparent .png image. (like photoshop does but ms paint does not)
dont take my word though cos it might be something completely diffrent, and I think most graphic cards ahould be able to support that.