I agree with this. Also, since the bullets are removed when hitting the player and the enemies seem to spawn at fixed positions behind blocks you can end up in a situation where there are no enemies and therefore no reason to shoot except to keep playing. Even a simple scoring system would go a long way here since shooting without enemies present is a net-negative in the game's current state. Movement feels slick though and I like the concept, you just need to add something to incentivize shooting!