The game may be a little short, but it's really fun to play and really well made. I find that the artwork perfectly suited for this game. The difficulty is very low, with an health bar, a shield ad 3 lives, but I guess you have a highscore system just for this reason. The theme isn't integrated in the gameplay, but in the story, and for me it's just as valid. Adding some more shooting power-up could greatly improve the experience and the fun