This is one of the better early, low budget Roger Corman films, not to be confused with the 1980 remake. Black and white.
As the movie begins, we see a young lady coming home from a date… being stalked by a sinister man wearing a suit, with dark glasses, carrying a briefcase. She runs but he catches her, and when he raises his dark glasses, his strangely radiating eyes kill her… and then tubing from the briefcase device harvests her blood.
Yes, it's a sci-fi vampire movie.
But it's got a certain amount of class. The sinister man is Paul Johnson, he lives in a nice home in southern California with a personal servant/driver, and he's seeing a doctor for a blood condition. He's also got a closet in his house that doubles as some kind of intergalactic communication device and teleporter, allowing him to talk to a 'floating head' that is his distant boss. And we learn that he's an alien from a civilization dying after interstellar nuclear war, and he's on Earth looking for a cure. So he's kind of a sympathetic murderous alien.
Jonathan Haze plays the alien's human servant, a flawed human being easily controlled by the alien's mental powers. Very characterful performance.
Along the way, he hires a nurse played by icy Beverly Garland (she was dating Corman at the time). Her character's boyfriend happens to be on the police force, so when she gets suspicious…
Also memorable is long-time Corman regular Dick Miller, who has the comedic role of the door-to-door salesman who knocks on the wrong door! (He ad-libbed his role from actual experience as a vacuum cleaner salesman!)
There's a scene where Beverly Garland's character takes a dip in the backyard pool, wearing a not-very-revealing swimsuit. This was considered very daring in a movie in 1957, but completely unremarkable today!
One amusing tidbit is that the actor who plays the alien got mad and stormed off the movie set one day. Some say the special-effect eye lenses were too painful for him, others say he had a drinking problem. So another actor filmed the rest of his shots, but you won't notice unless you look for it…
This is one of the more likeable of the early Corman sci-fi films, and it's still fun to watch.
Can you game it? You could make a pretty decent sci-fi RPG campaign based on this, but not a wargame, I would think. But I'm tempted to try a Hordes of the Things themed army:
* alien vampire (guy in suit with dark glasses and briefcase)
* female alien vampire (women with dark glasses)
* doctor and nurses
* car and driver
* hypnotized zombies
* weird flying assassin creature
The army design needs work but it has potential… 
IMDB: imdb.com/title/tt0050778
brings back some oldies.
