Interesting game to play. The line effect that you have implemented looks great! A few things that I noted, first, it doesn't actually feel like the player is going down and it's majorly happening because of the plain bg which seems to be at one place and not relatively moving with respect to play, secondly, It might be a bug, that once the player goes out of the screen, it loses the controls and move automatically in the same direction as it passed the screen forever. Lastly, if you add powerups and other such interesting things to the game then it would become really fun to play.