The Incredible Melting Man is a 1950s Drive-In creature feature made in the 1970s.
Fundamentally it has the same structure as, say, Monster A-Go-Go, or Beast of Yucca Flats. The comparison is somewhat deliberate, as like both films, it involves someone dosed by radiation, turning into a monster of some variety, and going on a rampage killing various people. In this case the film follows an astronaut from a flyby mission to Saturn. During the flight their ship is hit with massive amounts of radiation, causing two of the three crew members to be killed, with the third surviving. However, now his flesh has started to melt. The astronaut can check the process by attacking people and consuming their flesh, but only temporarily, and the process has driven him out of his mind.
Meanwhile, the police are trying to find the monster, along with Dr. Ted Nelson, the mission physician, and a general from the US Army, who is trying to keep this under wraps. This sets up the standard film structure – Monster kills people, the police and a scientist follow the corpses until they finally confront the monster in the film’s climax.
From some research, the film was originally meant as a general parody of this particular sub-genre of the horror film, with a more comedic tone. However, studio executives stepped in and tried to turn it into a more conventional horror film. This leads to a sense of tonal whiplash to the film. Some scenes have the General as a more sinister figure, while others have him in a more paternal role to both Nelson and the now monster-fied astronaut. As another example, there’s a subplot in the film with Nelson’s in-laws coming to visit, and all their scenes are clearly done for comedy.
Yet, on the other side of things, there are a whole bunch of set-pieces that are played for more conventional horror, with varying degrees of success. Part of this is due to the creature and gore effects effects, done by Rick Baker, who built up a considerable reputation later in his career, through such films as Men in Black. However, the tonal whiplash makes for a rough watch – and some clearly added padding (such as a several minute long scene of Ted Nelson’s wife knitting) also leads to pacing problems.
As it stands, the Incredible Melting Man is, instead of an intended parody of the “’50s Rampaging Monster” creature feature, closer to one of those films played straight, with a side of body horror. I wouldn’t necessarily watch the film by myself on its own, but it does work well either in the episode of MST3K where they featured it, or with some friends who are willing to help to make it funny.