PLEASE NOTE THAT THERE ARE MASSIVE SPOILERS UP AHEAD. EVERYTHING UP TO THE END OF THE STORY.
Please do not read the spoiler unless you have finished the game.
I finished Lost Odysey without completing ANY sidequests. My reasons for that have been a little bit more reactionary due to the lousy reviews the game was getting. By the time I got to the end, certain plot elements about the game was not clear to me. While I understand that the real value of the game is the emotional attachment the gamer will have with the characters, the 'sacrifice' towards the end made me wonder if everything will be ok.
By Disk 2 we realize that the immortals do not belong in the world that they are in. They are immortal because they are not native inhabitants of that world. Throughout the rest of the game, they never tell us what they were doing in the present world but Gongora claims that they were all traitors to their home world. And that's all we know at that point. As you progress, you will see the moment where the rest of the immortals lost their memories. But even then, you have no idea what the reason why they came to the present world. All their recollections only point that they originally belong to a world that existed in the same 'axis' as their own world. My understanding of this, is that the two worlds are parallel to each other.
As I progress, I never get to the point where the plot is expanded. Gongora continues to be an insane bastard towards the end. But I'm watching my husband play some of the side quests and then 'THAT' scene came. And suddenly everything seemed clearer and the 'sacrifice' was not in vain afterall. While that scene does not explain everything...it explains A LOT.
While we don't know if they will succeed in their mission, the possibility of a sequel to the game exists. It seems like Lost Odyssey is just a part of a bigger story that can unfold. And I hope that Mistwalker will be a chance to continue this unique story.