The adventure normally starts with a hook, often these are derivative or poorly thought out. There is an underlying assumption that the PC’s will choose to investigate a mystery despite their better judgement. Modern scenarios make better use of in media res to lever the action, but the difficulty remains - if you let players generate their own characters, how do you involve them without either railroading, or shattering player reality? Why do these characters continue to work together? There is a fine balance between the collective suspension of disbelief, and getting a viable group of characters to work together.
Next, the investigation phase. Old-School investigation games are like contrived intelligence tests. The players must ‘investigate’ following clues to get closer to the source of the mystery. If they don’t think of something, then they may miss out on a vital clue, and thus either get stalled, or be unprepared for the final scene. Often scenarios incorporate author assumptions that are flat-out unrealistic or unlikely, making further work for the GM. Options do exist in the game for the GM to prompt action, but these may well spoil the GM’s sense of reality. In addition, the ultimate result of such investigation hinges on some kind of successful skill test – a mechanical and luck driven intervention – in order to secure the information.
Obviously it’s in the GM’s interests for the PC’s to obtain the clues they need, but if such clues are made readily available, you once again risk the shared collective suspension of disbelief. Games like Trail of Cthulhu have highlighted this problem and made strong inroads on this aspect of the game, but the fact remains that making the investigation phase both challenging and rewarding without being boring or contrived requires considerable experience and skill and a high degree of flexibility on the part of the GM.
Finally, the conclusion – usually a confrontation with some action and probably some kind of strange monster. Again, the plausible ‘excuses’ the characters might have for venturing into the basement/secret chamber/old warehouse, and risking life and limb are probably thin at best. Considering the brutal nature of combat, and the imperviousness of many Mythos beasts, and the potential for losing a character to sudden temporary insanity - it’s likely to be a sticky end for some or all of the characters. If run straight, such a conclusion might be disheartening, un-empowering and feel like the work leading up to the climax was a waste of time. An experienced GM can work to make such a conclusion exciting, dangerous and meaningful, but I’ve come to realise that you’ve really got to have experienced Call of Cthulhu as a player first, in order to understand this fine balance.
And then, inevitably, the debrief – what was really going on? Why was it occurring and what could the investigators have done about it? Often frustrating, and an aspect of the game that really reinforces the old-school values of Cthulhu – the players encountered the plot, like some kind of giant, fast moving river, and were rapidly swept to the end, without really understanding what was happening or why. Sometimes these revelations are illuminating, but I always feel that they’d be so much better if they could be drawn out during the game, rather than afterwards.
I don’t want you to think I’m picking on Call of Cthulhu – many other games suffer from these kinds of issues, but what I conclude from this analysis is that most Call of Cthulhu games, if run as written, leave a lot to be desired, and have the potential to actually spoil the enjoyment of the players. To shape the adventure into the flexible and adaptive form it needs to be in order to negate such issues, requires a considerable degree of experience and skill. I guess, for my money, the problem is that this kind of consideration and discussion is not something that forms a core part of the game, and is certainly not an aspect of most published adventures.