Updated Roadmap/Overview. It seems as though many of you are experiencing problems with The Only Real Stopper even after making sure you killed every enemy by playing through a second time. On the other hand, it's unlocking without any problems for other people.
If anyone has any methods or tips on this achievement, let me know!
Currently Playing: Battlefield 4 (Xbox One) | Skyrim (Xbox 360)
Upcoming: Zoo Tycoon & Halo: Spartan Assault