So, uh, I beat it by sending three super soldiers down at the same time (note that sending only 1 at a time is a waste of money, as they never make $150000 before dying) and to get the money to do that, amass fifth generation, level 2 & 3 turrets on all of the turret locations (buy them) and send out a tank when enemy forces start getting hit by turret fire. Don't spam the tanks, only send out one. This way, it costs you $20,000 but you can easily get $40,000 per tank in what you destroy because of the turrets. It's a classic bait and switch tactic.
 "Gravity Bal"){kind=icon}
 "Mario"){kind=icon}
 "Bash Your PC aka MÉTELE AL ORDENATA"){kind=icon}
 "black crow"){kind=icon}
 "Escape From backwards Land 2"){kind=icon}
 "SHIFT 3"){kind=icon}
 "Hashi Ex Machina"){kind=icon}
 "Ether War"){kind=icon}
 "Age of War"){kind=icon}