Originally Posted by JOJOBASS
It comes down to proper turret placement (sniper turrets and flak turrets) and memorizing the waves. When you can remember exactly when a group is going to try to sneak in the backdoor so you can cut them off, things go much more smoothly. I managed to get it solo and my base was left at exactly 80% when I was done.
You should be my friend and help me get the gold