This is the only Metal Gear Solid game where the characters don't shout out one of the characters names if getting a game over.
This is notably the only canonical Metal Gear game that one of the playable Snake characters doesn't smoke. Snake does, however, briefly mention ordering a cigar during a certain recruiting side quest.
This is the only Metal Gear Solid game to not include character/voice actor names when they are introduced.
This is the only canonical Metal Gear game where one of the playable characters does not gain the infinity bandana, or similar special items.