Easy but fun
Fun. Incredibly easy though. Being able to go back to levels to get more xp if you can beat your previous best score is a great idea, but it's so easy to get all of the upgrades it totally kills the point. Removing xp gains for destroying rocks and possibly enemies may help with this. There needs to be some sort of limit on your firing rate you can easily keep 3/4 of the screen filled with bullets for more than half of the game. Bosses where absolutely devoid of challenge. Charging attacks is almost entirely useless. Movement is perfect, it truly feels underwater. The artwork is clean simple and fun to watch. Ripple effects are well applied.