I think the fact that your bots fire at the closest target is part of the strategy of it. Neither the challenges or the career would be hard if you had more control. If the game was completely different, more control would be cool. That being said, I found the career easy, you just have to make a good combo of bots. The challenges were challenging too.
 "Necronator"){kind=icon}
 "Use Boxmen"){kind=icon}
 "UPGRADE COMPLETE!"){kind=icon}
 "Bot Arena 3"){kind=icon}