Devastation Drive-In — 'Robot Monster' (1953)

Setting Seeds:  Robot Monsterpocalypse

Once The Ancients unlocked the secrets of atomic energy, it was only a matter of time until they discovered the most powerful weapon in the known universe:  the Cosmic Ray!  Intergalactic beings known as the Ro-Mans took notice, however...

...and decided that it was necessary to neutralize the threat posed by homo sapiens...

...BY ANNIHILATING THE ENTIRE HUMAN RACE...AND THEN DESTROYING THE EARTH ITSELF JUST TO BE THOROUGH!!!

An entire Mutant Future setting can be designed around an apocalyptic invasion from space by the Ro-Mans.  The ape-bodied mechanoids hail from the farthest reaches of space, and wield wondrous technologies that seemingly defy all scientific laws and principles:  teleporters, infinite-distance sensors and communicators, planet-eradicating weaponry, and even time machines.

In one potential Mutant Future, the Ro-Mans landed and laid waste to entire cities with their calcinator beams (or C-Rays), which instantaneously caused all of Earth's cities to crumble, and all life forms "above lepidoptera level" within to perish.

The only defense against the effects of the calcinator beam is an innoculation from an extremely rare antibiotic serum that makes the recipients immune to all diseases...and, inadvertantly, to death-rays from space.  So, those given the injections are now the last people on the planet, eking out meager existences in the ruins of civilization...all the while hiding from the Ro-Man hunters sent to exterminate them!

Ro-Man

No. Enc.:  1 (1)
Alignment:  Chaotic
Movement:  60' (20') 
Armor Class:  -2
Hit Dice:  350 hit points
Attacks:  2 or 1 (2 fists, 1 beam)
Damage:  2d10 / 2d10, or special
Save:  L20
Morale:  10
Hoard Class:  XVI, XVII, XIX, XXI, XXII
XP:  20,000

A Ro-Man is a stocky, 7' tall extraterrestrial construct with a gorilla-like body and a helmet-like head.  They have computerized minds and sensors.

Ro-Mans [sic] are powerful physical combatants, pummeling with mighty fists...and if both fists successfully hit in the same round, they can squeeze its target for an additional 2d12 damage.  But their brute strength is almost an afterthought when compared to their godlike powers. 

A Ro-Man can detect and focus on any and all sentient life on a planet, right down to the specific location of any given individual.  It is immune to all attacks and damage from any man-made weapon ("the arms of the entire world tried and failed..."), and all forms of disease, poison, and energy.  And one cannot forget their individual calcinator rays, which burst forth in a 100' radius and kill everything larger than a moth not treated with a special vaccine...with no Saving Throw allowed.  Ro-Mans are immune to the effects of their fellows' C-Rays.

There are only 3 ways to defeat a Ro-Man:  bypass its logic core with philosophical musings and emotional quandaries (in other words, teach it how to be "a hu-man"), entice it with a female Pure Human with a CHA of 13+, or have it be destroyed at the hands of its commanding officer, a being known as a Great Guidance....

Mutations:  Unique Mutation ("Calcinator Beam"), Unique Sense ("Life-Sense")

Ro-Man — Great Guidance

No. Enc.:  1 (1)
Alignment:  Chaotic
Movement:  60' (20')
Armor Class:  -4
Hit Dice:  550 Hit Points
Attacks:  2 or 1 (2 fists, or 1 beam)
Damage:  3d10 / 3d10, or special
Save:  L20
Morale:  11
Hoard Class:  XVI, XVII, XIX, XXI, XXII
XP:  40,000

A Great Guidance is the intergalactic commander of the Ro-Mans.  It possesses all of a typical Ro-Man's abilities and defenses, plus three unique powers.

First, a Great Guidance's C-Ray not only has twice the radius, but it is powerful enough to instantly slay a Ro-Man.

Second, a Great Guidance can unleash Cosmic Tube Rays, which open vortices into the prehistoric past and draws forth 2d10 dinosaurs into the present.  These reptiles berserkly devour every living thing—animal and vegetable—they encounter.

And, lastly, a Great Guidance can bombard a planet with "cyclotronic vibrations" strong enough to "knock [it] out of the universe."  These beams can shatter an Earth-sized planet to dust in only 3d4 rounds.

All of the above powers have no maximum range, and can be broadcast across space, and through communications media (vid-screens, etc.).

Unfortunately, the computers governing the Great Guidances are the most advanced in the cosmos, so appeals to emotion, reason, or philosophy go ignored.  Great Guidances are beings of pure intellect and drive, and never fall prey to human manipulations.

Mutations:  Unique Mutation ("Calcinator Beam"), Unique Mutation ("Cyclotronic Vibrations"), Unique Mutation ("Cosmic Tube Rays"), Unique Sense ("Life-Sense")