I don't know if all IF players of a certain age who witnessed the evolution and flowering of the inchoate genre from the late seventies / early eighties have a game (or games) which they return to for reasons of nostalgia or masochism, but mine is this one.
Having first cut my adventuring teeth on Scott Adams' Adventureland in 1983 on a friend's Vic-20, I played many of the early games both good and bad in the late eighties; this included Castle Ralf.
Like many authors of the time, Doug Clutter and Steve Vance had completed Zork I and wanted to try and outrun the boys from Infocom by forming their own company, Douglas Associates. While this was a predictably futile task, they undoubtedly did come up with a very well coded and interesting puzzle fest with precious few bugs present. Aside from the odd typo there are no glaring ones that I have ever came across in many hours of playing.
The "explore/escape from a wacky building full of contraptions" genre was of course already somewhat anachronistic by 1987 when this game was first published but it remains one of the best examples of its kind.
The robust parser rather oddly doesn't understand "take all" but does understand "drop all." On the whole however it is more than adequate and unlike many games of its type recognises most synomyms and objects in the many rooms of the eponymous castle. It also (rather atypically for its time) has a list of verbs on screen that you can access via highlighting and pressing the enter key so there is no hunting around for obscure verb / noun combinations. You can also use the COGITATE verb at many places to give you an abstract hint and boy will you need it as this game surpasses all but the Topologika games in terms of toughness but fairness in my opinion. The authors seemed to realise this and produced a hint booklet a la Topologika which is available online on this page. It runs to many many questions and answers and is designed to discourage straight through reading.
The game also features an auto mapper which can be switched on and off if you prefer not to use modern software like Trizbort and you will need it as the castle spans a basement and three floors over many more than a hundred locations. Initially the routes around the more far flung reaches of the building are time consuming to access, but as with games like Mulldoon Legacy and Curses short cuts appear to the various areas of the castle as puzzles are solved.
There are a number of complex machines scattered around the place, designed by the devious owner Dr. Bellefleur Q. Izgotcha III. One multi puzzle in particular involving a customised Skeet Shooter and a French Horn cum Crossbow spans multiple rooms filled with Heath Robinson like contraptions and more than rivals the Babel Fish puzzle from HHG in its complexity.
Many of the imaginative puzzles are more convoluted than "Do X with Y to get Z" but logically solvable with a bit (or a lot) of lateral thinking.
A dryly sparkling humour pervades the whole thing which stays just the right side of irritating. Try and COGITATE in the Long Dark Hallway for example! And apparently the Great Hall was designed by Nancy Reagan.
The game is mercifully free of mazes, hunger, thirst and light daemons and although it is possible to make the thing unwinnable in a couple of places this becomes apparent pretty quickly. Just save often. There is an inventory limit but it rarely becomes much of a problem as a chosen central silo to store all objects in is accessible from most parts of the game as it opens up.
The game runs very smoothly in my version of DosBox (0.74) and the colours are customisable.
I have to admit at this point that I have still not beaten the game after returning to it several times in the last thirty odd years, although I have recently pushed my score up to 190 points out of a possible maximum of 300. There is no walkthrough available anywhere online (something I never resort to anyway).
There are few NPCs in the game aside from an exhibitionistic Hamster, an avariciously psychotic Chihuahua and a useful ghost that I have ever come across.
There is also a strange obsession with hats which will gradually unravel as you play.
Castle Ralf was originally a competition game where the person to solve it in the least number of moves by a given date would pocket 10% of the royalties. I have no idea if this was ever claimed.
Now where is the combination to that safe...