i wouldn’t really call the potion codes in quest for glory 4 a copy protection since they are not at all required to finish the game. they are nice to have though if your a fighter, but not really even helpful for the other 2 classes, or at least not for me. i usually dont even bother getting them.
and the more i think about it, i think you are right that there isnt any in sq4cd. but like i said, i was just doing the list from memory.
and i think alistair is right, the list is complete except for some of non major series games.