Mechtropolis

Mechtropolis resembles an urban city at nighttime. It is the last/penultimate world depending on how you view it, as Null, World 9, is the win area. It also introduces Vigilante Droids, which act like basic Droids, but their daggers also do damage. Xero 3.0s can also appear, but only from Mystery Buttons or if other Droids are rerolled.

Mechtropolis has Turrets, which spin around, making a full cycle once every 10(?) seconds. It spits out bullets at a rate equivalent to Rapid-Fire Droids. Turrets aren't able to take damage, but will be disabled after their respective room is cleared.