Revisiting Horror Express For Your Old School Horror Gaming Campaign

This is one of those Public Domain movies that's just a bit of a cut above. The movie has a bit of everything for everyone. Its one that works so well as an adventure that I've run it numerous times.
 The basic outline and plot are from wiki :

"The following report to the Royal Geological Society by the undersigned Alexander Saxton is a true and faithful account of the events that befell the society's expedition in Manchuria. As the leader of the expedition, I must accept the responsibility for its ending in disaster. But I will leave, to the judgement to the honorable members, the decision as to where the blame for the catastrophe lies..."

In 1906, Professor Alexander Saxton (Christopher Lee), a renowned British anthropologist, is returning to Europe by the Trans-Siberian Express from China to Moscow. With him is a crate containing the frozen remains of a primitive humanoid creature that he discovered in a cave in Manchuria. He hopes it is a missing link in human evolution. Doctor Wells (Peter Cushing), Saxton's friendly rival and Royal Society colleague, is also on-board but travelling separately. Before the train departs Shanghai, a thief is found dead on the platform. His eyes are completely white and without irises or pupils, and a bystander initially mistakes him for a blind man. A monk named Father Pujardov (Alberto de Mendoza), the spiritual advisor to a Polish Count and Countess who are also waiting to board the train, proclaims the contents of the crate to be evil. Saxton furiously dismisses this as superstition. Saxton's eagerness to keep his scientific find secret arouses the suspicion of Wells, who bribes a porter to investigate the crate. The porter is killed by the ape-like creature within, which then escapes the crate by picking the lock.

The creature finds more victims as it roams the moving train, each victim being found with the same opaque, white eyes. An autopsy suggests that the brains of the victims are being drained of memories and knowledge. When the creature is gunned down by police Inspector Mirov, the threat seems to have been vanquished. Saxton and Wells discover that images are retained in a liquid found inside the eyeball of the corpse, which reveal a prehistoric Earth and a view of the planet seen from space. They deduce that the real threat is somehow a formless extra-terrestrial that inhabited the body of the creature and now resides within the Inspector. Father Pujardov, sensing the greater presence inside the Inspector and believing it to be that of Satan, renounces his faith to pledge allegiance to the mysterious entity.

News of the murders is wired to the Russian authorities. An intimidating Cossack officer, Captain Kazan (Telly Savalas), boards the train with a handful of his men. Kazan believes the train is transporting rebels; he is only convinced of the alien's existence when Mirov is discovered to be the creature's host when Saxton switches off the lights and Mirov's eyes glow. The creature has absorbed the memories of Wells' assistant, an engineer, and others. It seeks the Polish Count's metallurgical knowledge too, in order to build a vessel to escape Earth. Kazan fatally shoots Mirov, and the alien transfers itself to the deranged Pujardov.

The passengers flee to the freight car while Pujardov murders Kazan, his men, and the Count, draining all their minds. Saxton rescues the Countess and holds Pujardov at gunpoint. Saxton, having discovered that bright light prevents the entity from draining minds or transferring to another body, forces Pujardov into a brightly lit area. The creature/Pujardov explains that it is a collective form of energy from another galaxy. Trapped on Earth in the distant past after being left behind in an accident, it survived for millions of years in the bodies of protozoa, fish and other animals, but cannot live outside a living being longer than a few moments. The creature begs to be spared, tempting Saxton with its advanced knowledge of technology and cures for diseases. While Saxton is distracted by the offer, the creature resurrects the Count's corpse which attacks Saxton.

Saxton and the Countess flee the creature, but it now resurrects all of its victims as zombies. Battling their way through, Saxton and the Countess eventually reach the caboose, where the other survivors have taken refuge. Once there, Saxton and Wells work desperately to uncouple themselves from the rest of the train. The Russian government sends a telegram to a dispatch station ahead, instructing them to destroy the train by sending it down a dead-end spur. Speculating that it must be war, the station staff switch the points.

The creature takes control of the train as it enters the spur. Saxton and Wells manage separate the last car from the rest of the train just before the train jumps the track and tumbles to the bottom of a deep ravine. The caboose rolls precariously to the end of the track before stopping, inches away from the edge of the cliff.

The survivors quickly depart from the van while Saxton, Wells and the Countess gaze over the ravine to witness the inferno consuming the train and its unearthly inhabitants.


 Using horror express For Your Old School Horror Gaming 

Horror Express has a bit of everything in one very nice little package. From the UfO/ancient alien angle which is perfect for your Call of Cthulhu games to the characters as NPCs or patron showing up later in a retroclone game. 
The movie's setting can be used whole sale for steampunk horror game. The creature itself is lich with the power of possession that's usable as it likes. It may reanimate the dead three times per day. 

As a collective there could be more of these monsters within the cave in Mancuria and they might easily be discovered. The creatures might be even uncovered after a nuclear war so they could appear in a game of Mutant Future. 
Given the time frame of the creatures that the creatures operate they could show up in Labyrinth Lord or any retroclone game easily. So that the DM is not locked into the 1900s time frame.
 The movie is even adaptable to modern game where one of the train cars is uncovered and the beast's essence is still out there. The thing begins it rampage again and has new agendas.  What happened to those zombies that were "destroyed 
 What might happen with descendants of Professor Alexander Saxton and Doctor Wells  ? Could these gentlemen's families still be in the monster fighting business? Might they have been instrumental in the forming of an organization that has been watching the skies or the various locations mentioned in the journals of their forebears? 
Could the Russian government have a hand in preventing these monsters from appearing again? Even given the superior knowledge of a race like this the horrors of the knowledge that man wasn't meant to know might be far to much. 
 What about that cave back in Manchuria? Could that be a mega dungeon with a saucer at the bottom just waiting for the PC to uncover it?
 Who were the aliens that the creature came from? Personally given everything that the monk said and the various conversations the monster had with Saxon and the Wells. I believe that we're looking at an Archon.
 

 Everything about the monster fits the Archon arch type. Given all of the alien/devil stuff it all fits. According to wiki : The Bundahishn (iii. 25, v. z) is able to inform us that in the primeval strife of Satan against the light-world, seven hostile powers were captured and set as constellations in the heavens, where they are guarded by good star-powers and prevented from doing harm. Five of the evil powers are the planets, while here the sun and moon are of course not reckoned among the evil powers—for the obvious reason that in the Persian official religion they invariably appear as good divinities.^[13] It must be also noted that the Mithras mysteries, so closely connected with the Persian religion, are acquainted with this doctrine of the ascent of the soul through the planetary spheres
 More info can be found right over Here So in theory the adventure/movie could be even used with the Kult rpg