Easiest for me was to Terraform as high as I could, build on the plateau, and once I'm generating mana at a reasonable rate, flood the enemies once or twice with Water Storm. Then I pick off the survivors.
On Survival, when the missiles start coming - try putting out repair drones to draw the missile fire. I haven't found anything that will kill the missiles before they hit, so I hope they hit something cheap. Repair drones are the cheapest thing you can buy.
On the hard badge, the only one I had trouble with was getting Perfect on lvl 8 (Fan-tastic). And when I finally did get it, I could have SWORE I nicked the ledge before the flag. But it still went in as Perfect. Guess the game got tired of me. "Your key-banging irritates me! BEGONE with you!"
 "Reprisal"){kind=icon}
 "Drone Wars"){kind=icon}
 "Ultimate Santa Battle"){kind=icon}
 "Hanna in a Choppa"){kind=icon}