The Binding of Isaac: Rebirth

For this you need to turn into Beelzebub (will also unlock ''Lord of the flies'' achievement)

To do so you need to pick up at least 3 items that give flies.

You can have : jar of flies, ???'s only friends, BBF, Best bud, Big fan, Distant admiration, Forever Alone, Friend zone, Halo of flies, Hive mind, infestation, Lost fly, The Mulligan, obsessed fan, papa fly, skatole and smart fly