Martian Madness

Martian Madness is a Hardmode, post-Plantera invasion-style event that includes several alien-themed enemies. It can be triggered after Golem has been defeated. The event includes an extremely difficult boss, the Martian Saucer.

Martian Madness is triggered when a Martian Probe spawns randomly and detects a player (turning from blue to red), and is then allowed to escape. The event can be prevented by avoiding the Probe, or by destroying it before it can escape; although destroying it is difficult, as it flies off quickly once the detection occurs or the Probe is damaged. Once triggered, the status message "Martians are invading!" appears, and UFOs start flying in the background; though Martian Madness enemies will not actually begin spawning until the player is located at their spawn point.

Escape

 * It's possible to override it with the Pumpkin Moon, Frost Moon, or other event.
 * If you exit the world just before the probe despawns, the event may not happen when you re-enter the world.

Trivia

 * The Tesla Turret is a reference to Tesla Coils, invented by Nikola Tesla, which can look similar and are often used to generate arcing electrical discharges ("artificial lightning").
 * The Martian Walker is a reference to the tripod-like Fighting Machines from H.G. Wells' novel The War of the Worlds.
 * The name Martian Madness may be a pun of March Madness, the nickname of the NCAA Basketball Championship, played mostly during the month of March.