Beatifully designed and executed game. Cutscenes are pretty amazing use of. . . show picture I'm assuming? I don't know, it's wizardry. Lots of great touches, like the train car moving slightly over time.
UI itself is just so cleanly designed. Not sure how the card game itself was pulled off, but it looks spectacular and totally professional level. Like I could see this in Xenosaga or the next Final Fantasy as a side quest.
I thought the tutorial was ingeniously fit into the story, which turned out to be just a taaad predictible.
Gameplay itself is simple yet brain hurting.(in a good way). As mentioned elsewhere, its similar to Triple Triad, but I'd say a marked improvement. The inner/outer vertex differences and different game modes add a bit of strategy that is fun to puzzle out. Challenge level is good for a game jam. You can get to the finals on your starter deck alone if you try hard enough, and I wouldn't be surprised if you could win (didn't try that one).
Writing is decent too. I mean, Zachary is a total dweeb (10 years you fail to communicate, but continue to obsess?), but there's a little story arc that wraps up nicely. The characters all had their own personalities too, which is nice to pull off over just a few lines of dialog.
Game went a bit too long. Anyone interested in grinding DIa is going to take a bit longer than 30 minutes. I think you could probably get the game done in 30 minutes if you only did 1-3 optional battles to farm some new cards. I'm kind of interested in the post-ending content, but will have to revisit it later (and collect all the cards). Judges adhering to 30 minutes of gameplay may feel unsatisfied not being able to complete the story arc, but pretty much all the elements of the game are able to be experienced in 30 minutes.
Codes were also nice touch too (not thaaaat hard to find them all - just be bad at the game), and the rest kind of tells you where to look.
One bug I found - game does not fade back in if you lose to the previous champion in the post game content. It just remains black.