Great idea with combos keeping you alive! I had fun playing it, wish it was longer than 3 levels! You could add more sounds and with jumping you could try changing velocity in nonlinear way so it would feel better. Thanks to this jam I found useful article on that topic which you may like as well: https://chicounity3d.wordpress.com/2014/05/23/how-to-lerp-like-a-pro/