Admittedly I didn't notice what B did at first and thought the game was intended to involve stopping to fire at enemies. I almost prefer the extra bit of challenge from that.
The game felt rather simple, once you get a good strafe going you can easily go endlessly.
Some variety in enemies or attacks or speeding up as you go later into the game would help with this, as well as a hi-score implementation, like typical arcade-style NES games.
Music was the highlight for me, pretty solid chiptune track!

I like the way the pumpkins move in before they attack you. They so angy!