Wow. This was amazing. I just added this game to my Steam wishlist. It is visually beautiful, and the game play was a lot of fun. The level difficulty scaled nicely, and while there were a few puzzles that made me stop and think, nothing was so difficult as to make me want to skip it. I felt it was a good length for a demo, though definitely wanted more.
The folding mechanic was pretty clear and it made sense how and where you could and couldn't fold space. Unfolding took me a little longer to figure out, though once I acknowledged the color change it helped. You might want to have a comment about needing to be close enough to the line in order to unfold.
The music was nice, but it was pretty quiet, particularly compared to the SFX. I needed to turn the SFX slider to be nearly 0 while the BGM was at max to be able to hear the music without the SFX being uncomfortably loud. The SFX worked really well, I just wish they had been balanced a little bit better with the music.
I played the game on the web, and worked mostly just fine. After beating level 28, I got a blank screen. I had to refresh the page in order to do anything. After refreshing, the level selection let me pick levels 1 through 5. Once I beat level 5 again, I was able to select any level on the level select screen, and selecting the ??? gave me the end/full version coming soon page.
I really enjoyed playing this game, and I am looking forward to the full release.