Steam Sale Dom3 players might like.

[Sombre]

They also used to ask stuff like 'what's the third word on the second line of the twenty fifth page of the manual?'

But honestly I don't think this form of copy protection was ever effective. Those who would actually copy the games were connected to the 'scene' and knew the workarounds. Even when I was very young there were cracked copies of games being passed around. Nowhere near as prolific, but then games were nowhere near as prolific either. I doubt the actual % has changed.