While it's long been my contention that most old school adventure modules were what I'd call "location-based" scenarios, I recently realized that I neglected to include another possibility: "problem-based" scenarios. Scenarios of this sort don't necessarily focus on a single location (though they may), but on a single problem that the adventurers must resolve. The problem can range from the simple -- put an end to the orc raids on civilized lands by slaying their leader -- to the complex -- investigate the disappearance of a human colony on the edge of space -- but the problem plays a similar role to the location in location-based scenarios, namely providing a backdrop against which the characters perform their actions.
A good example of a problem-based scenario is a murder mystery. In murder mystery modules, the characters are faced with uncovering who killed someone and why through the uncovering of clues that allow them to piece together the truth. Adventures of this type are particularly difficult to pull off well, both in terms of presentation and in terms of execution, which is why modules like 1982's Murder in Harmony stand out even after nearly three decades. Written by Mark Acres for Gangbusters, Murder in Harmony concerns the murder of Arthur Overton, a wealthy musician and president of the Amalgamated Musicians' Union. Overton was shot dead during a brief blackout at a cocktail party at Harmony Manor, Overton's stately home and it's up to the PCs to solve this mystery.
I remember Murder in Harmony for several reasons, chief among them being that it was the first truly successful murder mystery module I ever ran. I'd run murder mystery adventures before, but they were always of my own devising, so I knew their intricacies backward and forward. One of the dangers of problem-based adventures, as I stated above, is presentation. How do you present the referee with all the information he needs in order to run the module effectively, especially if there are a large number of details, many of which are red herrings or at least ancillary to the central problem of the module? Murder in Harmony has no simple solution to this, instead opting for a series of grouped sections -- chronology of events, keyed encounters, testimony, physical evidence, financial records, wiretaps, etc. -- all of which the referee is expected to know well, or at least well enough that he can easily find the information he needs when the characters start poking around.
The other thing I love about Murder in Harmony isn't really about the module itself so much as about the type of old school play it (and Gangbusters itself) exemplifies. All of the clues that help the characters resolve the central problem of the module can only be found by looking in the right places or asking the right questions. There are no mentions of "a DC 15 Gather Information check reveals ..." or "Succeed at an Observation roll to notice ..." in this module. Instead, the text assumes that the players, through their characters, will try and think things through on their own, collecting information by visiting the crime scene, interviewing witnesses, and generally employing basic investigative techniques to amass enough clues to point them to other clues that might enable them to resolve the central problem of the module. Murder in Harmony is thus very much about challenging the player, not the character, which I think is an important feature of old school gaming.
Make no mistake: Murder in Harmony is a challenging module, both to run and to participate in as a player. The referee needs to know a lot of information, as the text is jam-packed with details, a great many of which, as I noted, are irrelevant to the mystery of Overton's murder. Players must rely on their own wits and intuitions in order to know where to go, what to look for, and whom to interview if they have any hope of solving this mystery. Now, truth be told, the mystery isn't all that complex or difficult to unravel; in some respects, it's fairly conventional, especially when looked at within the context of crime stories and films from the era. Nevertheless, there are no freebies in this module. The players are largely thrown on their own resources to find the clues that can establish the truth beyond a reasonable doubt and bring the perpetrator to justice.
Running Murder in Harmony when I was a teenager was an important part of my gaming education, which probably explains why I retain such a fondness for it even now. I'm sure that it could probably be better presented than it is. Much of its text consists of large "info-dumps" of names, places, times, and other details that the referee must become comfortable with and that means lengthy preparation beforehand. I doubt I could easily run a module of this sort nowadays, not without a more streamlined and user friendly presentation. But, back when I was a kid, I had all the time in the world and I had no difficulties in spending hours getting everything just right so that I could have fun with my friends as they tried to solve the mystery of Arthur Overton's murder.
My lasting impression of Murder in Harmony, though, is that it presents a style of play I still find compelling, one where the player is every bit as important as his character, probably moreso. I remember people who insisted that this module's mystery was "unsolvable." That's far from literally true, but it does speak, I think, to the fact that, if the players don't make the right choices, they won't be able to unravel the mystery this module presents. Personally, I think that's how it should be. After all, what's the point of a mystery if it doesn't require that -- and I mean you, not your character -- try to puzzle it out for yourself?