That is all you really need to know about the game and a deep understanding of the lore of Middle-earth is not required to enjoy the game, though there is a codex with information on all of the characters, items, and such that you come across in the world to give you more information on them if you want that.
They kill Talion and his family, sacrificing them in order to bring out a specific Elven wraith spirit to help them, but he instead possesses Talion to help him get revenge for the horrific death of his family.
Of course, Sauron can never leave things like this alone and sends out his Uruk forces to take out the outpost that is guarding the gates. Middle-earth: Shadow of Mordor features Talion, a ranger of Gondor that is helping to protect the Black Gate of Mordor with his wife and son at his side. The newest game in the Middle-earth world puts the focus on being a fun game over being a vessel of story and lore and benefits greatly as an awesome game for Lord of the Rings fans and newcomers alike.