I've also made a shoot'em up game last year december in a day or 2 to celebrate the silliness of Doge Coin.

I did make use of the moving background to increase the sensation of speed when speed power up is taken( Eventhough i know the background should not be moving at all :P)

http://tensaix2j.github.io/tothemoon/

Anyway.. Just to share. Have fun.