The aesthetic for this game isn't my style, but there's no denying it works really well. The UI and music just look really polished, and you even have some filters (film grain and the scan lines over the character avatars) to make the game visually pop.
That said, there are a couple UI things that I found a bit annoying which should be easy fixes. The dialogue and music buttons take up a lot of the screen, and I'd rather just have a settings button for music and a popup for dialogue that went away completely after the cutscene finished, as they take up a lot of real estate and make the game screen look cluttered. The controls on the right also seem cluttered until you realize they're there for mobile players. This could potentially be something a desktop user could hide to free up more space, but it's less important. Finally (and this is really a 5 minute fix) I was confused by the fact that the only way to tell who the player is controlling is the "ACTIVE: 1" indicator at the top of the screen (and the sparkles, which only pop up for a fraction of a second and then are gone completely.) Why not have some kind of effect or even just a color change over the active player character?
One more small nitpick regarding presentation is that the amount of juice in the transitions and the quantity of dialogue (which is kind of cliche) make it feel like too small a percent of the time the player spends with the game open is actually gameplay, which only becomes more annoying with the puzzles themselves being so easy. I finished this game feeling unsatisfied, and while the level creation system hypothetically allows players to enjoy more content and more difficult levels, it feels a bit like outsourcing an important part of the game onto the player when the content included in story mode is so lean.
On a more fundamental level, there's an interesting concept here, but I REALLY didn't like the level design. Most of the levels are braindead easy, and the ones that are even slightly hard hinge entirely on keeping one of the characters trapped until the end of the level. Sliding puzzles where a character can only stop when they hit an obstacle are common, and the idea of being able to manipulate an obstacle (the capybara) so as to put the sliding character in optimal positions is a novel twist, but if all of the difficulty comes from keeping Capy locked away in a little area where she can't help, your level design has undone the exact mechanic which differentiates this game from every other slider puzzle.
I get why you made an easy game. Harder games score significantly lower on the site and it's clear whoever designed the game knew their audience. At the same time, there are ways to reward more skilled play, even if basic completion of the game is easy. The most obvious idea is to keep count of how many moves the player has made, and recognize if a player is able to complete the same level in fewer moves.
4.5/5 for a really solid concept, but I'd like to see a player pack flesh out the content with a bit more difficulty and replayability.