Here's what you do:
You switch between a girl moving in a 3D space and her independently moving shadow. The girl does a lot of block pushing while the shadow does a lot of platforming in a 2D space, but both will need to work together to pull switches, solve puzzles, and move forward. There is spoken and written dialog throughout the game. The girl, her shadow, and a third voice will speak to each other and some of their thoughts will be written out on the stage objects and backgrounds.
What I like:
I like the platforming sections of the shadow. I thought the game would be mostly focused on puzzles, but there are some paper birds found throughout the game that take some advanced level platforming to reach sometimes. Other birds are a more advanced puzzle solution than the one needed to progress. The birds only reveal puzzle pieces to images on the level select screens. Each of these screens also helpfully tell you how many of the birds you have collected. This is very helpful to anyone who wants to 100% the game. The game's art style does look very nice.
What I don't like:
The girl's high pitched voice seemed very out of place at first. I don't think it goes well with the messy-haired girl that looks like she might be out of a horror film. The shadow has a deeper voice, and I think they are supposed to be two personalities of the same person? That would make sense, but the game does not give conclusive answers about who any of the three voices are supposed to be. Most of the game is the three voices arguing with each other over vague concepts when they finally just get over it in the final chapter. Also, that scene in the trailer where the girl pushes over a piece of prop scenery and she dives into the light, that is part of the very end of the game. The ability of the shadow to possess other objects is only done in the last chapter. The game sticks to moving blocks and platforming the entire rest of the game. The puzzles do get difficult, but by the end I was getting tired and wished they could change up the activities more often.
The game's characters seem interesting at first, but you never get to know any details of the drama the girl is going through. She may just be fighting extreme shyness. I lost interest in the characters halfway through and was enjoying the gameplay, but that eventually got tiring by the end. The game is about six hours long and has great visual design, but it is not something I will be returning to any time...