Not the main story, but one of the modes, Slaughter, how long can I survive, not a bad attempt really, lots of achievements and medals and upgrades and stuffs.
...
https://www.youtube.com/watch?v=SLciPWeCOZI
Communication from the other side, are they aliens? They seem to not care much about human life that is for sure.
...
https://www.youtube.com/watch?v=a7LNvMRXLRU