I like the many tanks you have and the coloration of them. Defently better than the first one. The looks of the tanks were amazing. I love the leech tank, it's a menance, the ability to get more bubbles auto matically and has virus thingys.
The attack buttons from your ship though should be slightly darker or the enemies is slightly darker because it's hard to see the color differnce. it would be helpful if your ship was darker too. Could you maek the ping noise softer? I would love to have the abilty to save the gave whilist on it.
Also would it hurt to have the person to change the primary shoting? I had to pause many times because my con. tablet made my hand hurt.
For the next one, make the audence chose what the next powerups should be. For example they get only to chose one wepon on the first level up. They can also select what they want the ship wants to look like. (but don't really explain, let them figure it out or posibly have it so the wepon makes the shape of the ship). When they level up more, they are able to select weps and 2nd weps based upon the current shape/size of the ship. And they select the ship again. and after each level it can auto save and then after they reach max lev they can save whenever they want.