From the review:
"There are a couple of controversies attached to the game.
One of them, I'm right there with a lot of the early reviews. The “Ranger Mode” DLC is bullshit. Paying $5 to unlock a difficulty mode labeled as “the definitive Metro experience” is just so unspeakably ridiculous, I have to wonder what the hell the developers were thinking. Seriously, guys, ochen nyekulturnee."