i have to comment yet again, this game is so F'N buggy!!! in survival mode, i worked until i got two Silo Drones... then they just stopped working- they wouldn't shoot! and targeting things is a bitch! i want the card, yet hate the game!!!!
horrible game. so many things wrong. thanks for making your game window a rectangle- nothing like having a strong enemy come from above or below, leaving you with zero chance of getting two shots off. i got the achievement, then got the F out.
 "Drone Wars"){kind=icon}
 "Understanding Games: Episode 4"){kind=tracking}
 "Snowman Attack"){kind=icon}
 "Tarnation"){kind=icon}