Software piracy is illegal and unfair to the people who make and sell games. That's enough of a deterrent for most people. The rest may find the giant, invincible, super-fast, assault-rifle-wielding scorpion monster more convincing.
That's the new DRM measure enacted by Serious Sam 3: BFE developer Croteam. We see the potential for this to become an industry-standard method of preventing unauthorized game copying. Or, in simpler terms, if that scary-ass monster wants to go into other games, we are powerless to stop it.