Warhammer 40,000: Space Marine - Inquisitor Drogan Gameplay Movie
Inquisitor Drogan's wound slows down the Space Marines as they battle Orks.
Well actually, it's not that easy in many sections, especially when you've got orks up in your face and more raining down bullets and rockets on your head from on high. And it's only worse when you get later on in the game- you'd be surprised how fast your shield and health goes down when you're being shot at by five or more enemies.
Indeed doesn't seem to be very hard. I remember the demo being quite challenging on Hard, encouraging you to use every weapon and move you had to survive.