I really feel like this whole story fits better if you change Talion to one of the human kings who became the Nazgul. Think about it, at that time Sauron was totally taking over various human kingdoms and maybe he kills this guys family the guy finds one of the nine rings(maybe he kills one of the other wielders) goes on a quest for revenge. The whole time the ring is speaking to him guiding his choices as this spirit figure and granting him more wraith-like abilities, Talion spends the game killing the "allies" of Sauron based on the spirits advice while also killing off terrorizing and bending to his will the weaker orcs and creating his own army to fight against the dark lord. Hey presto, he gets to the final battle and finds that the spirit has been Sauron the whole time. He looks back on his actions and realizes that the whole time he'd been trying to fight against the dark lord he'd become more and more like him. Maybe even some of the enemies were actually men fighting against Sauron.
The game fits with the Tolkien view of morality(I.E. a wrong action for a good cause leads one further towards evil) and is a nice little comment on how morally ambiguous the actions of gamer's tend to be in games when in pursuit of their goals. Plus they don't have to create a whole bunch of stuff wholesale they can work with what Tolkien already left kind of vague (We know next to nothing about the men who became the ring wraiths) also it makes much more sense for Talion to get his powers this way instead of some really angry elf just happening to take over this guys body like two thousand years after he died.
The game fits with the Tolkien view of morality(I.E. a wrong action for a good cause leads one further towards evil) and is a nice little comment on how morally ambiguous the actions of gamer's tend to be in games when in pursuit of their goals. Plus they don't have to create a whole bunch of stuff wholesale they can work with what Tolkien already left kind of vague (We know next to nothing about the men who became the ring wraiths) also it makes much more sense for Talion to get his powers this way instead of some really angry elf just happening to take over this guys body like two thousand years after he died.