Martian Madness

The post-Golem alien invasion set off by an escaping Martian Probe.

Martian Madness is a Hardmode invasion event in Terraria, available after Golem, in which alien-themed enemies spawn in place of the usual ones. It begins when a Martian Probe spots a player and manages to fly away.

Quick Facts

Type: Invasion event (Hardmode, post-Golem)
Triggered by: An escaping Martian Probe

Facts from the source article.

Background

Martian Probes appear at random in the outer thirds of the world, more often in the Space layer. Once a probe detects a player its lights turn red and it tries to escape; attacking it does not count as detection, and the invasion starts only if it gets away. UFOs then fly in the background, but the event's enemies can only spawn near the world spawn point or near town NPCs. A progress bar tracks the invasion, which ends after enough of its enemies are killed. It can only begin when no other invasion is under way and at least one player has 200 or more maximum health.

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