I really want to like this. It's a good game at its core, with absolutely phenomenal technical skills with both spritework and character design. The story is well-crafted (albeit somewhat predictable) and there's an interesting theme of grief throughout.

What bothers me, though, are the environments. As well-realized as they are on a technical level, I find that they're quite dull to explore since they're mostly just going to be cave systems and stone ruins with some aesthetic rejiggering between them. They're very fancy rocks to be damned sure, but you can only look at rocks for so long before you get bored of them and with some exceptions its all you're really offered.

The pirate ship areas are certainly more interesting to look at with the wood and clockwork theming, and I certainly enjoyed the final area, but I never found myself really going "oh, that's neat" despite orchestral swelling trying to cue me into an emotional response.
This lack of forethought results in areas feeling fairly unimpressive unless you have a deeper appreciation for the technical skill on display. Which as a pixel artist, I do! And I've learned a lot about my own craft playing it! But I still can't help think what more it could have been with just a bit more effort spent on putting the excellent art direction of the characters into the environments more.

I also think the core mechanic of free-flight held the game back significantly, Otus and friends certainly control well but you can feel a TON of places throughout the game where the designers were struggling to really balance that freeform movement, often relying on simple timing puzzles and narrow navigation corridors to funnel you into properly engaging with challenges. And it doesn't always succeed, or specifically has to cheat sometimes to make it work.

An example that comes to mind are bomb enemies in a narrow vent system. Normally, these bomb enemies can be stunned with one of your buddies, and you ARE able to summon your buddies when on the vertical stretches since there's room to summon them. However, the bombs are special ones that cannot be stunned, which feels like a strange choice since there's not really much challenge to them already. Why NOT let players get a bit of fun juice out of circumventing a very minor navigation puzzle?

The bosses are also somewhat of a balancing roller coaster. The hardest boss in the game is about 3/4ths of the way through the game, and the final boss though VISUALLY spectacular is kind of easily defeated by just spamming attacks at them. It actually undercut some of the finality of the ending as well.

The story is also odd. There's a major secret you can only get on newgame+ that just unlocks some story lore, but the lore that it gives you is just minor background context to smooth over some of the evident plot-holes. They do a fine job at this, and there's even a fun bit of prophetic misdirection if you're really paying attention to the wording and story, but it also feels like a strange reward for going so out of your way. Feels like that secret was meant to be a bit more than it was, but had to be cut for time. I suspect there's an unused boss lurking in the files somewhere that just didn't get completed.

Also, that cannon minigame is atrociously difficult. It feels like there were supposed to be more of them that got scrapped to get you used to the mechanics, but only the most difficult version wound up making it in, and even after numerous attempts I found myself failing to reach the end. You also only unlock faster movement after a 100% completion on coin collection, which winds up pretty grindy and obnoxious after a wpell.

Overall, I think this is an interesting game to play if you have an interest in pixel art. There's a lot to learn about subpixel animation, detail clustering, and dither patterns if you are willing to study what you're seeing. Otherwise, I can't honestly recommend it beyond a 6/10 rating. It's certainly above average, but small areas of low polish and underbaked concepts hold it back.