X: Beyond the Frontier

One of the "modern" games with real nasty copy protection. It could be copied pretty easy and no one would expect it when just checking if it works - but somehow, pirate copies tended to "cheat" the player. You wouldn't get the right amount of money for goods, goods would be lost somewhere for no good reason, quests would be finished by the player and counted as not finished or vice versa - and the best: it could happen after hours of play :)