Definite and possible cinematic & literary inspirations:
The Friday the 13th series:
Splatterhouse's hero looks just like Jason Voorhees, but of course is just an average guy, college student Rick Taylor, wearing the "Terror Mask".
The disembodied hand seen in all of the Splatterhouse games seem to be a reference to the film Evil Dead 2: Dead By Dawn, in which the hero of the movie, Ash (played by Bruce Campbell), cuts off his own right hand with a chainsaw after it's infected by the evil awoken by the Necronomicon. The hand (now with a life of its own) goes after Ash and tries to kill him. The same scene is shown in the sequel, Army Of Darkness, even though the hand doesn't show up in the movie.
Supposedly the mansion in the original Splatterhouse is the mansion of Dr. Herbert West, from H.P. Lovecraft's Reanimator.
Jojo's Bizarre Adventure:
The "Hell Mask", also know as the "Terror Mask" or simply "The Mask", despite looking like a hockey mask, is intended to be an Mayan sacrificial mask, like the one in the anime/manga Jojo's Bizarre Adventure.
I've found new stuff that links both the Evil Dead and Splatterhouse series. First, in both cases, the Mask/Necronomicon has been found by a scientist in ancient ruins.
Then, in the three Evil Dead movies, flying objects (poltergeists) are very important and deadly, like in Splatterhouse.
In Splatterhouse 1, Jennifer becomes a monster, and tries to kill the hero, like in The Evil Dead and Evil Dead 2.
In Splatterhouse 1, Rick must fight his image in the mirror, like Ash does in Evil Dead 2 and Army Of Darkness.
Rick and Ash both have a chainsaw and a shotgun as favourite weapons.
In Splatterhouse 2, blood floods the room while in the level with the undead fetus hanging from the roof. In Evil Dead 2, blood floods the whole room after Ash tries to kill his possessed hand.
Splatterhouse 3 has very similar stuff: there are horrible flying corpses covered by drapes in Splatterhouse 3, and there are arms with claws which go out of their mouth to grasp for Rick. At the end of The Evil Dead, after killing the zombies, the very same horrible hands come out of the corpses to grasp for Ash!
In Splatterhouse 3, as Jennifer is infected by the boreworm, some kind of black web spreads under her skin, which is the same visual effect as in The Evil Dead when the girl (perhaps she's also called Jennifer, I don't remember) turns into a zombie.
From Psychadelic Death:
I noticed something when looking over the characters for SH: WG...The clock and deer head look like they might be Evil Dead 2 parodies...
In Evil Dead 2, there's a clock that stops whenever something's going to happen. In one scene Ash has a mental breakdown where he sees everything in the house laughing. The first object that starts laughing is a deer head mounted on a wall, that's followed by lamps, bookshelves curtains and other inanimate objects laughing.
Another possible movie that may have influenced Splatterhouse. These are some trivia facts I wanted to add (tho not 100% sure):
The teethed slugs from the original Splatterhouse look identical to those from the monster/gore movie Deadly Spawn (1983). A lot more than say the baby alien that bursts out of chests (but the ones in Deadly Spawn were based on them).
Here's a bit of info about a possible musical influence on Splatterhouse 3:
For any of you Splatterhouse music buffs, it may interest you to know that the music played during SH3 's opening demo (when the diamond spins endlessly) sounds incredibly similar to one of the songs that can be heard throughout the 1986 film Gothic.
Although I have always thought highly of the Splatterhouse score (particularly with regard to the second instalment of the series), I find it somewhat distressing to know how uncanny the music sounds in comparison to the music of Gothic . Seeing as how Gothic was published in the mid-80s, this may mean that yet another apparent factor of influence has been uncovered (unless the verbatim is all an unintentional coincidence).
From Chris Eisenlauer:
Chris has clued me in on another film that Splatterhouse may possibly have been based on - or, at the very least, Namco may have gotten the concept for the Mask from this film. Check it out and decide for yourself.
The Mask (1961)
Summary (from the IMDb) - A young archaeologist believes he is cursed by a mask that causes him to have weird nightmares and possibly to murder. Before committing suicide, he mails the mask to his psychiatrist, Dr. Barnes, who is soon plunged into the nightmare world of the mask. Summary written by Jeff Hole (email@example.com)
From Lane Graff:
Here are some more possible cinematic inspiration for events and creatures throughout the series:
Here are some of the movies that (Namco) put in their (Splatterhouse) games. I cant prove that they are based off of these movies but if you look them up you'll probably agree with me.
The Burning - Splatterhouse: WG (the shadowy figures with the silverware in their hands).
The Dead Pit - Splatterhouse 2 (when Jennifer is held over the pit and hands reach out and grab her).
Zombi 3 - Splatterhouse (when you punch the large head demon guy and his head falls off and flies at you).
In Splatterhouse 2 the heads are tossed at Rick from the final boss come from different films. The one with its mouth gaping open is from The Fly (1986), the most human looking head with the wormy looking things is from From Beyond, and the one with the sagging eye is from The Toxic Avenger.
From Stu MacBride:
"As most people know, while Rick has the Mask on he looks just like Jason Voorhees from the Friday the 13th movies, but Jason doesn't wear a mask until Friday the 13th Part 3... in Part 2 Jason wears a bag over his head, just like "Biggy Man". Here is an image I made comparing the F13 characters to the Splatterhouse characters."
From Joe Drilling:
"...the Splatterhouse ads for the TG-16 version were a reference to ads for the original Last House on the Left, which stated "In order to keep from fainting, just keep repeating 'It's only a movie, only a movie, only a movie, only a movie (etc., etc.).'" Check it out here.