I like a lot of its ideas but I hate the overall thing and let me get into why.
On the surface Chi is a great idea. A fantastical fairytale retelling of the ancient war we've known about since the first game. A story that manages to not ruin the mystery of the past by using familiar figures and places to sub in for the actual ones. The idea that places like Agrabah and people like Alice weren't really there, they were just being used to represent things that were. That's what was billed to us and when it was just that it was great, it was simple, and we didn't really need anything more than that. We had a group of mysterious figures in animal masks revealed to be the ones who organized the armies that fought the keyblade war and we just needed to steadily move towards the war. Ultimately we could have had a nice self contained story that would have brought new light to a much wondered about period in the series's history, but Nomura is never happy with just leaving things.
Instead of having a natural conflict of people loving the light then eventually fighting over it to the point their greed escalated to a world destroying force, we have this weird and largely unnecessary future element brought in. Now instead of a regular human conflict we have this weird concern with the fact they know the world will be destroyed hundreds of years into the future. Like I mean that's what makes this the most bizarre is their worry first and foremost is about stopping the second keyblade war. The first war that is written in the book doesn't even seem to be on their mind until near the very end. I mean if this was maybe 20-30 years in the future or at least at a point in time where it was going to affect them soon that be fine, but no this is so far removed it's like how we are told the heat death of the universe is inevitable and instead of just accepting that one day everything has to end we start spending our lives fretting away our days trying to stop something so far beyond our control, something that won't affect anyone alive at the time for hundreds of years. It's just such a weird thing to have them focus on and make the upcoming much more immediate war that will only "nearly" destroy the entire world and will kill them basically an afterthought. Which all ties into the bigger problem of how because they go to great lengths to justify how everything even the disney worlds are literal the past no longer has any real identity of its own, that's lame. Just like how it's lame that the keyblade graveyard apparently was ALWAYS a barren war torn wasteland.
From this everything spirals and gets worse. Apparently they were collecting lux in order to save the future but how was this going to save the future? It's never explained and while we later learn lux can summon Kingdom Hearts it turns out that was forbidden and thus not the goal any of them were knowingly working for most of this. Was there even a plan or were they just doing what the MoM told them to do? And oh man the MoM that is just where things go from bad to worse with the foretellers. None of the Foretellers show any sense of will or logic of their own. They know their master can see the future ergo he already knows who the traitor is, he knows Ira is going to fail, he knows everything is going to become a hot mess...and yet not one of them questions it. Ira doesn't question being putting into a position of leadership that he is destined to fail in or the Master's complete indifference to the upcoming destruction, Invi doesn't question the ominous remarks the master says about being left behind and how things have to change, Gula doesn't question why the MoM didn't just write down the traitor's identity nor does he question the Master's plan of "take out the one who doesn't follow their role" when we later learn at least a handful or roles were kept secret, Aced doesn't question why he is literally given a task that literally is betray Ira if he doesn't think he's doing a good job, and Ava doesn't question why everything about the dandelions have to be hush hush. She at the very least questions what the point of keeping the unions is but the MoM dodges it and again she doesn't question it. Like what it boils down to is none of the foretellers had any agency of their own they were just really cool dressed robots. It makes Backcover ultimately a rather unenjoyable watch because you keep expecting maybe a little humanity, maybe even a glimpse that there is substance to these people, but instead they just blindly listen their Master's every word and react in base and predictable manners. Also don't get me started on Nomura's blatant lie "I decided to leave it clear who the traitor is in Backcover" no at best he made the MoM the most likely suspect but he did a horrible job telling us who the traitor is.
It just doesn't stop there though because we have increasingly more weird things. The nightmare chirithy subplot that goes nowhere, Chirithy being a dream eater not having lead to any sort of meaningful reveals, and on the subject of Chirithy that's just one more thing the foretellers don't question. The master can see the future, he should already know that creating the chirithy leads to the nightmare chirithy, and thus no one stops to question if that is worth the risk of the cute little creature existing as their helpers. Compound this with just how badly written the whole bangle thing was. Alright a bangle that is billed as capturing darkness and converting it to light is not a bad idea, the idea that they get spread around and were actually a trap to make union wielders use darkness so nightmare chirithy are born and wielders start to descend into darkness is also not bad. But what is bad is how they write the foretellers in response where apparently they knew about the bangles and even though they knew it was the same as using the power of darkness they allowed it and deemed it okay...because why? Why is that a good idea especially when NONE of you know where those bangles came from how on earth could you possibly screw up THAT bad just a few weeks after your master vanishes? A more competent way to write them would have been for them to worry about the bangles, say it's not okay for the union wielders to use them, but then go on to say it's already too late. The bangles are out there all over the place so it's too hard to bring them back now, a nightmare chirithy already exists, and the last thing they want to do is stir unrest in the unions by announcing the truth of the bangles. But no they just allowed something completely counterproductive to their cause with no clear origin scott free and then start panicking like chickens with their heads cut off.
The stuff with Ephemer, Skuld, Chirithy, and the player are all interesting and well written. But how I wish when the past is struggling with holding onto a little bit of its own identity they would stop slapping characters from present day into the age of fairytales. Like I wanted answers about Ventus and Marluxia's past but what I didn't want is to get those answers in a slow burning phone game that is going to have now come up with SOME kind of complicated excuse as why these characters are alive in modern times if they were from the fairytale times. It's doubly insulting when they introduced an interesting new female character, gave her a week's worth or so to exist in our hearts, and then replace her with a character who again really shouldn't be here. Also as said by many in other topics even if she does come back it doesn't change that killing off one of our few KH female characters for shock value was really cheap and totally unnecessary.
There is also other minor grips I have where this story seems to be retconning a lot of stuff. The keyblade war was fought over the X-blade and Kingdom hearts...except both of those elements are completely absent during the actual war. The keyblade was a tool created for conquering the light and using it to defend the light came later is completely contradicted by the fact all the keybladers at the start were using the blade to defend the light and conquering it came later. There is also an absence of any regular people in the past...like part of what made the keyblade war story so good is that implication that after these super powered wielders went and ruined things killing themselves in the process it was up to regular children and the few remaining wielders to rebuild the world. But we don't see a single real regular person in Chi, they can't all have been wielders so is it so hard to at least get a few regular people so the world feels a bit less...small?
If we could just do away with the prophecy nonsense, the tome of prophecies, the MoM being behind all the foreteller's actions, the past allowed to have its own identity, for things to line up with what little we knew about the war, and some proper explanation for things instead of everyone being a walking frustrating question mark then I'd like Chi a lot more. Alternatively one of my best friends made a Backcover abridged that pretty much covers exactly why I don't like Chi's plot.
https://youtu.be/JvZGXpIJnBE
But that's just my feelings on the matter I don't mean for anyone who likes the story to take that as an attack.