It's worth noting that one of the key influences behind The Immortal was Will Harvey, formerly known for other games such as Zany Golf. Somewhat of a difference between fantasy minigolf and this one...
It was ported from the Apple IIgs to the Amiga, Atari ST, Megadrive/Genesis, IBM PC and NES, and there's probably more than that out there.
When I first discovered the game (on Sega Channel) I was awestruck by both the grotesque violence and the cackling glee in which the game seemingly arbitrarily punishes the player. After awhile of playing, you do figure out the game's tricks and can avoid them most of the time. This game would definitely be banned in Australia under the current regime, and I remember the NES version (which I played later) was rather sanitized by comparison. Thanks, Nintendo!