Uh, it isn't any real accomplishment to finish that game within a few hours. I went through the entire solo campaign in just a few hours. Besides, its not that hard since you reach a checkpoint every 5 steps. Seriously, the game is like...
Holy crap, these stairs are hard to navigate, here's a checkpoint in case you die.
*Walk down stairs
HOLY CRAP, you made it. Here's another checkpoint in case you can't make this corner... And so on and so forth. Save for one spot at the end of the damn metro. That was kinda annoying.
But really, this game is best in co-op. Because then you actually have to protect each other and crap like that.