Fallout New Vegas
(How the bloody hell did Rob not guess that already)
DING-DING-DING.
Okay, making each clue about NCR Rangers might not have been the best idea.
1. Even devils fear the men in black.
Pretty much every faction in the game hypes up the Veteran Rangers in their black armor. Including the Legion and Fiends.
2. One shot, one very messy kill.
The opening cutscene has a Veteran Ranger sniping a fiend with an Anti-Material Rifle.
3. Chew nails, spit napalm.
NCR Troopers say that the Veterans Chew nails and spit napalm.
4. Big Iron~
OK, this one really isn't directly about the rangers. but the song Big Iron plays a lot. Which is ok because it is awesome.
http://www.youtube.com/watch?v=pPArO-OI_3U5. The only way they could be more badass is if they rode those bears instead of waving them around on some flag.
The NCR flag is a two-headed bear and some of the Veteran Ranger art has one standing beneath it.