Well there wouldn't be any canon characters to play. Gandalf went to Valinor with Frodo, Bilbo, and others. Legolas and Gimli have done so as well. Aragorn is dead. Eomer, Faramir, and pretty much anyone from the books is either dead or gone to Aman. Thranduil is pretty much left unless you count descendants of Dain Ironfoot and maybe some others who were never really POV or major characters for the books.