Look! A short review! (Which will get more 1ups than my novels do...)

ZAU is a short, beautiful Metroidvania that's light on the Metroidvania and light on depth. You might get Ori vibes from the lush backgrounds, but don't be fooled, this is nowhere remotely on par with Ori.

There's a heavier emphasis on combat, as you have two masks, the moon and the sun, which you can freely change between and which change your combat abilities. The moon form has a ranged light attack that requires a short recharge after shooting 8 (you can spend skill points in the required-by-law skill tree to make that 12 and to add a timed button press to quick-refill), while the sun form... mostly just is inferior. Sure its light attack doesn't run out but it's a 3 (upgradeable to 4) hit combo and it's slow and you will get interrupted. Oh and the moon form can get an ability to reflect projectiles, which is nice.

So anyway, it's so light on the metroidvania they're literally just going to give you double jump and dash from the get-go. You'll unlock a very small set of additional abilities, most of which will be briefly used right after you get them, and then maybe once later on when they remember they should do that. (This goes up slightly if you are going for 100%.)

There's a story here about a young man dealing with the loss of his father and trying to bring him back and ... honestly, I don't know. It feels like it's steeped in some cultural traditions that I'm in no way qualified to speak on. I'm not sure the writers are either, from some light reading I did on the topic.

Mostly this fell flat because it wasn't ever really challenging except for the optional platforming challenges which get you trinkets (think charms from Hollow Knight, yep, we're still doing that). But the trinkets are only useful in combat and a vast amount of combat can be trivialized by shooting enemies from off-screen, because they won't retaliate. Or literally standing on a platform higher than them and shooting straight down at them because they have no jump. Yeah, it was pretty boring after a while. The boss fights are more interesting, but there's a grand total of 4 in the game.

It was free on PS+ so if you're a die-hard Metroidvania fan, you could probably check it out, but I wouldn't actively recommend it.

Wrote a comment and now I can finally write this review.
Story 10/10. Absolutely beautiful representation of dealing with loss and really great to see another culture highlighted for its own rich story and customs.
Gameplay is probably 6/10 at best.
Combat goes from really easy to kind of odd and difficult for no reason, to oh I can now walk through everyone with one move. Not enough exploration either. Every time you enter a new section, the entire map is automatically given to you. There's very little to go and discover on your own and the game is pretty linear. I actually think it's a decent "my first metroidvania" since it's fairly easy to complete.

4 stars but closer to 4.4/5. Again, the story told is enough to give this one a play. I was seriously moved by it.