I like the art style and the catchy beat that's playing in the background. I think a small thing that would have helped with instructing the player would be to have them press the spacebar at the start rather than enter. That's pretty much the only button they'd be using, so introducing them to that at the very beginning make how to play a little clearer.
Also, could you tell me what you used to develop this? Was it an engine or raw HTML5? I'm looking for other methods of developing games for browsers so I can participate more in future jams like this.