Okay! I had zero idea what I was supposed to be doing. And if it weren't for me trying to play enough to give meaningful feedback I otherwise would have quit almost immediately. I thought I was supposed to line up the numbers 1-9 since that's how many slots there were but when I made a row nothing happened. I don't understand the correlation of the colors since nothing happens when they touch. I finally looked up the rules and I would never have figured out I needed a chain of colors to do things. I think just some kind of visual feedback will help the player a lot. Some kind of Ding or Sparkle to let them know they're on the right track. If I need to stack 3 boxes but when I stack 2 nothing happens, I'm not very inclined to even TRY the 3rd box, you know?
Otherwise it has the makings for a fun little idle puzzle game, like Minesweeper or something. I liked that I didn't have to wait for the dropped cube to go all the way down before I was able to move the next top cube, that was good. It functioned and the UI made sense! Really great look to it.