Martian Madness

Martian Madness is an upcoming event in the 1.3 update, announced by Cenx in the April Fools' spoiler. It includes several alien-themed enemies, among them the Brain Scrambler, Gigazapper, Gray Grunt, Martian Engineer, Martian Officer, Ray Gunner, Tesla Turret, and an as-yet unnamed tripod enemy. The event also adds the Martian Conduit Plating, a new item of indeterminate function, and the vanity item Martian Costume Pants.

The 1.3 music spoiler track plays during this event. (listen)