I only know the second part of grandia, but it is great!

(There does not seem a story connection, though)

There's a fan theory that Grandia II is a prequel to Grandia set in the far, far, far distant past. I think the main basis is from one of the final scenes in Grandia II, involving two people with wings - possibly be very first Icarians (Grandia's ancient nonhuman civilization).