Those badges seemed pretty easy to me. All you need to do is dedicate as many hours as possible to finding 7 people, then you just need an automatic weapon, aim for the heads and you're pretty much sorted. Admittedly I got the headcount on the very last level but still simple enough game
That was pretty easy, 621 on first go. Make sure to glance the sides of the smaller, quicker ones and then play around with the big ones, don't just fire them off the screen as this will boost your score
 "The Last Stand"){kind=icon}
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 "Luminara"){kind=icon}
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 "Dolphin Olympics 2"){kind=icon}