The initial concept seems good, but the big problem of the game is the pacing, you start with a lots of cubes to keep your atention, but if you do well there is a moment where you don't get more good squares spawned and you can only kill yourself.
I recommend to keep spawning good and bad squares all the time and make them quicker as the time advances. Also, it would be more challenging if you had more trayectories for the squares, like diagonal directons, or maybe even circular movements like spirals or something.