1. Didn't think about that I will fix that for the next build
2. I will mess with the gravity scale a little to try and fix the floatiness. With the horizontal movement I made some improvements and I think what feels off to you is that fact that as soon as you stop pressing on the key the cube immediately stops. I did this on purpose to make the movement a little unique.
3. That's a good idea I will do that for the next build.
4. Agreed, this is still just a demo so I haven't spent a whole lot of time on the music. I plan is to add an instrument for each color that is added so the level 1 music will stay about the same but the others will have more to it.
5. Why not use Time.timescale = 0 for pausing? Do it cause problems for the game?
The game is a long way from being released on steam. This is just the demo, it will be much better when it's time to release it on steam and I am proud of what I have done.