This looks cool. The UI animation is good. Looking forward for more such games. A few minor feedbacks.

1. Even on phones, it leaves a lot of margin/padding, and the boxes are a bit too small. Can you make it a bit more responsive and use up the whole width of the screen (up to a max width of course) 2. Only the first and the last needs to be selected, and so slide doesn't work. 3. A minor confusion in the UI, that I'm not sure if the equation can span across multiple lines?