This was a really good time. All of the things about the game were fun.
I've seen a game with a similar mechanic, Camera Obscura, where you manipulated platforms by taking still frames and moving them around. This game took a similar idea and beefed it up a bit with a touch of reality bending and the ability to move and walk on light, and that's pretty rad. The art style for the game is unique, with most things looking a little like paper, whether that's intentional or just my own view on it. The environment itself is full of life and little details, but remains subtle enough to not distract you from whatever you're doing. It's one of those games where if you actually stop and look around, you go "Whoa, that's a thing." I always appreciate games with detail like that.
Overall, the audio was pretty good. The music was pleasing to the ears and all the voices seemed good matches for their characters, but I did notice that there was a little inconsistency in the quality of the voices. Some characters were louder or quieter than others or sounded as if they were recorded through an inferior microphone, perhaps. Being a demo, however, I'm assuming this was strictly a technical limitation and give it a pass.
I can only say so much about the quality of gameplay, since it was a puzzle game. The controls were functional and everything responded as it should and the puzzles themselves were well done. I just happen to not be very good at puzzles, so that limits my opinion on the matter, eheh. And while it might be an odd thing to take a lot of notice of, I thoroughly enjoyed your work with the lighting effects and how the shadows moved, grew, and faded according to your movements. Very good work there.
I show it in my video, but I ran into a bit of a bug with the postcards. No clue what triggered it, but I looked at one and suddenly it wouldn't go a way. That may need to be looked into.
Great game overall though. Keep up the good work, I look forward to the finished game.