Thank you very much for the detailed feedback.
Yes, you are right there are quite a few things to fix, I didn't test intensively because working on the game in one day, including making the drawings and animations, took a good percentage of time.
Definitely I will improve it, since a lot of people seems to like the idea.
Yes, slowing down tanks, might do already a big difference.
In my test, I could manage to complete level 1 destroying the enemies, though lots depends on the weapon you get and the enemies you face, since all is randomised. In the second level I could destroy half of them, after I have to run too to the exit.
The thing to keep in mind is that enemies too have limited ammo and there is friendly fire. So, they are immune to their own bullets only, aside for the mortars if I recall well. That means that you need to try to get tank 1 missiles hit the other tanks. Same thing with the other weapons.
You can try it again with this piece of information, maybe you can kill a few tanks :-)
Thanks again for trying it!