Ruvik, and many of the other mutilated boogeymen that Sebastian encounters, simply can't be killed. You can shoot at them all you want, but all you'll get for your trouble is a Game Over screen drenched in Sebastian's blood. Your only option, then, is to run in the opposite direction, as fast as Sebastian's miniscule sprint meter will carry you. And run you will, because usually, it's instant death if your pursuer catches up.
Besides providing a thrill during cinematic, bone-chilling set pieces, being hunted by an immortal monster is also a recurring game mechanic. At random intervals, a blue pulse will fill Sebastian's head. That means it's time to hide or die, because Ruvik is roaming around near your location. If you don't take refuge underneath a bed or inside a wardrobe, Ruvik is likely to find you and disintegrate your body with a single touch. Whether this will be annoying or enthralling has yet to be determined, but it's certainly a good way to keep you on your toes.