I really think this game idea is amazing and can be improved on. I understand what you mean by you just want to get a game out because you keep dropping projects, I've been through the same thing. Here is a small list of things I made while playing:
- It was hard to tell when I or other entities were moving because the flat green background, maybe add a grass texture to make it easier to read.
- It was very tedious to shoot people to get a small amount of points. Maybe make people take less hits and give more points
- The tanks were very small, hard to see, and hard to shoot. Maybe make the sprite a bit bigger to reflect the power of a tank.
- I purchased the "mech" upgrade and I have yet to see any mechs around the map.
- I feel like the combat is a bit anticlimactic. You shoot them a bunch and then they just disappear. A good way to improve this is to add some screen shake and some particles. Just try and make it have more juice and be more satisfying.
- Sound effects and music are a great way to add some juice.
What you have so far is a great proof of concept, but if you want to continue to polish this idea, I would heavily suggest to look at this list. From what is there, I really like this idea and would love to see where it goes!