There's a fan game called Dark Millennium that linked PS2 and PS3.
The first time Earth is mentioned is in PS2 with spaceship noah (Noah's Ark/Sea_ship v2).
In PS3 (at least in one ending) there is a link to that PS2 ending (because they really show Earth) -> a very cool idea.
It's a pity that they didn't explore the concept further. For instance:
A) space ship noah came in 822AW to Algol Solar system - could have come before 126AW to create an "event loop" because that was the year spaceship navigation was created in Parma. It could also explain some religious artifacts and so on. Could even be (years latter) the cause for Lashiec knowledge about DF... but no, it had to be 822AW.
B) in PS3 if earth wasn't populated yet by humans, palmans (who have their planet destroyed) could be the very first humans... I mean the genesis of earth; even GL would be called "God" by them and so on. So many years latter that palmans would call themselves earthman and in the future they would come to Algol to take that star system. (This would be very funny, but no... the planet was already taken by real earthmen.
So the great thing about earthman is that "Alisa III" crashed on Luna/moon (or didn't crash at all). The earthman took Algolian technology, knowledge/information and routes... and then found out that a solar system called Algol would be perfect for them to live. So they departed and arrived... yes at 822AW (they only waste time because 464 years latter they were (completely?) exterminated.