This is a very interesting prototype. I am looking forward to see more update.
Some thought when I play through the game:
1. All turret requre platform and turret. Thus, unless we have different construction paths, it can simplified as buying any turret incress the cost of all turret.
2. Range is under rated. Blaster can barely defense one side of the base. Meanwhile, sniper can cover all four side of the base even without the upgrade. DPS and overkill doesn't mean anything if the bullet can't reach the asteroid.