That's a great strategy, until you have Mark II Jetpack Robots on your tail.
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Yes, they are monsters! >:)
I wanted to make an enemy type that could kick the ass of my best players, but some of the Titanium levels have so many of them that they might be a little bit too far on the ridiculously hard scale. Once the update has been out for a bit I'll have more data on the win percentages of each level, and might adjust some of the ridiculous ones to be more reasonable.