Now, this may sound like a side note but it's important. I know because recently I showed the original Rondo to someone who knows only the newest CV, plus the very first.
You need the unity of the metroidvania formula nowadays, or it will look like a little gimmick game: think megaman and its separate stages. They can be the funniest, greatest stages full of secrets and interactivity... but will never compete with the awesome wholeness of being playing in the one big world of CV.
CV3 was incredible, I still remember buying it at the shop: having seen OOE (long plain stages like CV2), even the level design would be ok but the world must be one. And more than OOE's: imho we need a different engine which can handle everything without you ever crossing a screen border.