In my opinion, for something to be a unique game on a particular platform, it has to have not been released on any other platform and has to have a totally unique narrative. I could care less about the graphics, the game engine, the character models, changes to the map, changes to the means of killing enemies or anything else. Those can and often are changed when a new platform comes along and a company decides to re-release a title in an enhanced form. If the fundamental narrative isn't completely unique to the game (i.e. not just re-translated or reworked or added upon), it's just not a different game. I have no issue with calling RE on Gamecube a heavily enhanced version of Resident Evil and certainly worth playing through again even if you have played the other versions of the same game, but in my opinion, that doesn't make it a unique game or a platform exclusive.