Is it just me or are some of the Challenges for Steampunk Tower just a craps shoot? You need a bit of luck, and you need to override the auto-targeting. I've micromanaged my way past some of the levels, but I'm stuck on 11, 12, 13, 14. Maybe I'm just going about it the wrong way. Does anyone have a strategy for beating those levels without actually needing to override the turret AIs? I love craps, but the Steampunk Tower challenges are just aggravating.
I'm also stuck on the challenge for 4, but I'll figure that one out eventually. Probably need faster reflexes ore re-prioritizing my targets.