The first game isn’t strictly necessary to understand what happens in Baten Kaitos Origins, since Origins is a prequel set about 20 years before, but it does have quite a few references to characters that show up in the other game to reward players who know what’s going on.
Story: You play as Sagi, a spiriter just enlisted in the Dark Service. He’s got a mechanical puppet friend named Guillo, a machine which is a bit more than the typical puppet (though they’re not telling the Dark Service that). But when his first mission leaves Sagi framed for murder, he and Guillo are suddenly fugitives. And then they stumble across a giant creature which provokes Guillo into some frightening abilities . . .
Milliarde (Milly) joins on your way out, and from there on it’s a crazy romp through floating islands and a dream-land that Sagi keeps entering whenever he encounters one of the beasts. Unraveling the mystery of these “afterlings”, stopping an ambitious politician’s attempt to promachinate the world, and uncovering dark secrets about the word and themselves is par for the course.
It’s hard to say too much without spoiling some of the better plot twists, but overall I love Baten Katos Origin’s plot. I think it generally improves tremendously on Baten Kaitos. The fact that there are only three party members means they each contribute significantly to the game, there is a major arc involving each one, and the inter-party dynamics is a huge part of the humor and drama. Guillo and Milly’s infighting brings out some of the best humor of the game. They all have such a personal stake in what’s going on—and Sagi in particular has a shocker of a revelation that makes what looked like a plot contradiction with the first game something that works perfectly.
Also, Baten Kaitos Origins continues the Baten Kaitos conceit of making you, the player, an actual character in the game, as Sagi’s guardian spirit. There are some rather obvious pauses in some of the spoken dialogue to allow for your custom name, but it’s still a win to have the characters talking directly to you and involving you in their decisions. (Sagi, as an aside, is much nicer to you than Kalas was, which is doubly ironic considering how both of them end up).
There were a few oddball moments, though. Anuenue bogs down the plot due to the sheer amount of backtracking and running around doing little errands to get the action going again (tip: the Holoholo bird and chicks is not the nightmare fight it’s made out to be, as long as you favor ex combos with Guillo with finishers that hit multiple opponents. He’ll kill both chicks every turn or two, allowing Sagi and Milly to focus on healing and/or damaging the Holoholo bird, who wastes the fight respawning the chicks). And one of the villians at the end was a total shock in a bad way, in that I’m still scratching my head trying to figure out why it happened at all.
(And don’t turn the game off too soon! There’s an extra scene after the credits.)
Gameplay: Baten Kaitos Origins, like Baten Kaitos, uses card-based battles with cards called magnus. If you think that sounds boring, watch a short clip of a fight on Youtube—these are very fast-paced, particularly as you level up the ability to see and discard more cards at once. The game rewards long combos as well as specific types of combos (called Ex combos which will boost your damage). Battle cards range from standard attack cards anyone can use, to character-specific finisher attacks, to weapon/armor/accessory cards, to healing, to various modifier cards.
Out of battle, there’s also quest magnus, which are generally environmental things you can “draw” for help completing puzzles, boosting stats, or upgrading equipment cards. Along with the quest magnus you get mixer magnus, which allow you to combine the quest magnus to make new magnus. Any recipes you create get filled out in your library, so you can easily refer to them later. The library will also store any Ex combos you’ve done, magnus you’ve collected, and enemies you’ve fought, so it’s a nice way to see everything.
Unlike Baten Kaitos, only the quest magnus decay (usually getting worse with age), so there’s much less deck micro-management (and your battle healing items no longer become useless on you, yay!). You can also create multiple decks, if you want to balance them differently (eg, a multiple-enemy deck versus a single-enemy deck, or a boss deck with more healing versus a random encounter deck).
There’s also a Coliseum, although it’s worth mentioning the Coliseum has a rather significant bug if you make small talk with the receptionist before unlocking Vega that will cause Rank 5 never to show up. In general there are some nice prizes and it offers some optional boss fights near the end for a good challenge.
Overall: I would recommend a guide (GameFAQs has many good ones) if you’re interested in the sidequests or filling out the Library, but generally going through the game isn’t too hard by itself. The story is very good, managing to support and subvert Baten Kaitos all at once. It’s a shame the game never got a lot of attention, as this packs a lot of highlights into one game. I rate this game Highly Recommended.