First of all: You call the music / sfx placeholders, but actually they are great! :) The game itself runs very smooth, and it is kind of fun to play. But very hard! I find it especially difficult to adapt to the controls when using a keyboard, maybe it would be better to have only "turn left/right" instead of "turn into direction". Probably the controls are designed to work with a gamepad? Maybe you can add an option for keyboard + mouse controls?
Overall the game is nice and has potential when you improve on the controls and the graphics. Well done!
PS: The leaderboard does not work for me.