Despite Serious Sam 3 promising to fight piracy simply by being an awesome game, it turns out that developer Croteam has snuck some DRM in there. Fortunately, it's the best kind of DRM -- the kind that only affects illegal copies, and hilariously trolls pirates.
If your copy of Serious Sam 3: BFE has not been obtained through the official channels, a miniature pink Arachnoid will chase you throughout the game. The gun-toting scorpion cannot be killed, and it will pursue the player at a rapid pace. Serious Sam 3 can be tough enough as it is, but the Arachnoid's presence is designed to make things tortuous.
This is the kind of DRM I can always get behind, because paying consumers are not punished and the pirates cannot say that it's exactly unfair. They got what they paid for.
Serious Sam 3: BFE – DRM Introduces Immortal Scorpion [Dark Side of Gaming]