The game Earthbound for SNES had code that detected if it was pirated or not. If the game knew it was pirated, it would still quietly run... But it would make

The game Earthbound for SNES had code that detected if it was pirated or not. If the game knew it was pirated, it would still quietly run... But it would make the enemies so difficult and powerful that you could barely get out of the first town or even enjoy the game. Oh and as a bonus it would delete your whole game right before the final boss.