Tips for Mad Scientist (getting all upgrades):
Choose a town you can make 100k+ (Brisbane, Ottawa) on and let your zombies start their chain. Choose MJ but don't activate him. Gather money and watch the population count. Just before the town is destroyed activate MJ which stops time, lets you gather money, and hit SKIP to end the stage before the town is destroyed. Activate MJ sooner than later until you get the timing down.
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