This game is really fun!!
Even though I played alone it was fun to play around, but it would be great to have a bit more to do while you wait for other or just something to do alone in general, f.e. a shooting range with moving obstacles or something .
Even though mostly everything felt very smooth and polished I noticed that when you shoot a big missile the tank stops immediately, I'm pretty sure thats on purpose I just thought it diddn't feel thtat good/polished/weird.
Apart from that I really only missed a different controll pattern like the Arrow Keys but with the q/e keys being used It's not that easy.
In conclusion it looks good for now, keep working on it :)