This was not my first Dark Parables game, but it's been so long since I played the Little Mermaid one that I forgot a lot of what makes the series stand out.
The basic concept of the games--playing as a "Fairytale Detective" who is investigating mysteries that are tied to well-known fairy tales--is interesting enough on its own. But there are also smaller aspects that really solidify the experience.
As you play and interact with the environment, find hidden objects, and solve puzzles, you also occasionally find little pictures. Collect enough of them in one set, and you unlock parables. These are the stories that each game is loosely based off of.
In this case, there were four different parables to unlock. Each was a story revolving around swans, darkness and light, and royalty. The game overall is noted to be "based on Hans Christian Andersen's The Ugly Duckling and the Catalan folktale The Water of Life, with elements of the Spanish Estadea and The Children of Lir."
The game's version of the stories is simple enough when I reflect on it. Without saying too much: young princess and prince meet, make a promise to each other, meet again years later, but princess forgot and King tricks the prince to avoid marrying off his daughter. The princess is cursed to live in her portrait until she finds the Water of Life. You're investigating the aftermath of those events. I felt pretty bad for the Prince through most of it.
Sometimes, it was actually a bit hard to follow because I'd be picking up notes that the prince wrote about the betrayal, bits of paper with the story, messages concerning the investigation, and then reading the parables themselves as they unlocked. It was sometimes difficult not to mix up the "main" story with other tidbits that were being collected, because that same main story is a mashup of all of the others, picking and choosing certain aspects. Of course, you're also not really getting everything in chronological order, so it's not like you're just picking up a direct continuation each time.
The art is seriously beautiful. The environments are rich and detailed, and the HOPs are really well-designed. Some games in this genre throw hidden object scenes at you that just don't make sense, or are otherwise very bland in their attempt to camouflage the items that you're looking for. In this series, you're faced with more realistic scenes to sort through, like the one pictured below.

It's an old, abandoned wagon/carriage that the princess traveled in, so you see things like her drawings, stuffed animals, cushions, clothing and jewelry, etc. The things you're looking for are usually smaller parts that combine into three larger parts of a whole object that you need to continue your investigation. For example, gems, pieces of necklaces or brooches and the like, to make a fancy emblem that will unlock a chest somewhere. The scenes just make sense, and I appreciate that a lot.
The actual puzzles were interesting and mostly fun. There were a few that were frustrating, but puzzles are the part that I enjoy the least about these games, which is just a personal thing. I just like the interactive and hidden object parts way more.
The music was also very enjoyable. There were a few standout tracks that just felt perfect for the setting.
I'm going to play the first game in the series next. I'm excited to see how the series has developed, since I've only played later installments.