Here is the full list of all 35 Alphadia I & II achievements worth 1,000 gamerscore.
Watched the opening of Alphadia I.
Took the two and went to the resistance's place.
Enah joined the party.
Got found by the pursuer.
Gained a ship.
It was revealed that Maxim was Karim's brother.
Gained an airship.
Victor died.
Fought with Maxim.
Reached the ending of Alphadia I.
Completed all the subquests of Alphadia I.
Received the Beginner level Credit completion award of Alphadia I.
Received the Intermediate level Credit completion award of Alphadia I.
Received the Advanced level Credit completion award of Alphadia I.
Received the Master level Credit completion award of Alphadia I.
Watched the opening of Alphadia II.
Visited the hometown in the escort mission.
Worked together to deal with energi distortion.
Leon passed out.
Survived thanks to Ash.
Jaguar died.
Head out to the final battle in order to stop Ash.
Reached the normal ending of Alphadia II.
Reached the true ending of Alphadia II.
Completed all the subquests of Alphadia II.
Received the Beginner level Credit completion award of Alphadia II.
Received the Intermediate level Credit completion award of Alphadia II.
Received the Advanced level Credit completion award of Alphadia II.
Received the Master level Credit completion award of Alphadia II.
Cleared the Beginner level of the arena.
Cleared the Intermediate level of the arena.
Cleared the Advanced level of the arena.
Cleared the Master level of the arena.