This is cool! I like how both the enemy bullets and the player bullets share the bouncing infinitely property, so even if you limit your shots, the enemies sure won't, and things get out of control regardless. One thing I noticed is that the game is fairly easy if the enemies aren't aggro'd on the player. You can just shoot one shot and let it bounce around until the enemies are all dead (though I guess the timer helps to mitigate that strategy).
Keep up the good work! =)