NIce game! Looks and sounds good. I think, that adding health and speed to enemies during time will make gameplay more interesting.

This felt oldschoolish and nice, I'd create some additional enemy variations plus maybe tighten the controls up a bit (acceleration and especially deceleration were a bit too much for me, but I guess that could just be my personal taste), then proceed to publishing to the app stores, it's simple yet charmingly so. :) Well done!