I love the idea, and I can see it being a great game to play with friends, or for streamers to play with their subs. A few points I would recommend:

• The tanks should be a bit more balanced compared to the others. The yellow one is clearly lacking in offensive abilities compared to the green one, for example.
• A little quick result screen after the level would be cute to see. And, if the levels are co-op, showing who's MVP would be nice and make some friendly rivalry... hopefully friendly.
• More options for multiplayer and singleplayer would be nice, such as turning off friendly fire. Even silly options such as moon jump or double impact, where the damage isn't double, but the impact of it hit is.
• Should've checked before typing this, but having the jump button on the shoulder buttons (maybe L or LB) by default would help. Had some difficulty jumping and aiming at the same time.

But, that's all I could think of to help out with advice. Already wishlist this game on Steam, and look forward to the final release. :D