they did that with Batman Arkham Asylum. http://kotaku.com/5356752/deliberate-glitch-foils-arkham-pc-pirates but like any form of piracy deterrent it only lasts a while til its cracked.
I enjoyed how Batman did things, where they checked to see if the copy protection was gotten around and so made it impossible to get past parts of the game. Or who can forget GTA 4, where if you cracked the game your player was CONSTANTLY drunk, lol... These are extreme examples, I mean you could just put a notice saying…