Where do I begin... well, first, I just want to say that i've purchased most(if not all) of Azurezero's games(on other websites), and Phantom Thief Sylphy being the newest of Azure's works at the time of writing, i'd say it's just alright.

I'll only be talking about the design as a game, not the story.  Phantom Thief Sylphy  isn't unique in mechanics among H RPGs, but it's definitely more of a game than most H RPGs out there. It's not exactly fun, either, as running back and forth to solve the easy puzzles gets a little tedious after some point. The minigames are at least a little creative, and it shows that Azure's willing to try to design games with a little more to offer, and I like that. Also, the game is super laden with bugs, some of which are gamebreaking, so make sure to save often.

The music and sound are all stock RPGmaker MV assets, so nothing to write about on this aspect.

As for the visuals. Azurezero's art isn't the best, or that good, but I personally appreciate the artstyle. If I didn't like the artstyle as much as I do, I honestly wouldn't have bought Azure's games, because well... they're alright/mediocre.

With time, I expect Azurezero's games to improve, and they definitely have. Is Phantom Thief Sylphy worth the $10 pricetag? Personally, i'd say not really, maybe $7.50 or so, mostly because the game is short, but if you're a fan of Azurezero's works, definitely pick it up at full price.