There was a time between the Mordor you remember from the movies where it was inhabited by people from Gondor and was a thriving area while Sauron was away for centuries in the far east. Now, the whole spirit of Celebrimbor is a hot new take (also one I didnt mind) but they did a good job of staying true to what Mordor was probably like during the time.
Origins was a great new step into the franchise. Battles flowed great, the weapon system was well done, a few boss fights were welcome changes of pace. Only downfalls were it had way too many cut scenes to develop a story line and the characters you know and love were out of reach, as you had to be the nameless main character (unless you had a companion).