Miscellany: Running a "Call of Cthulhu" campaign, part 5
The first duty as a game master, whether it's being a Keeper in "Call of Cthulhu" or anything else, is to the players. While there's certainly nothing that says you must kowtow to their every whim, listening and responding to what players do and don't like about your game is almost essential for everyone to have fun. There's almost nothing worse than an imperious Keeper who doesn't see fit to mess with the rules every so often.
My group wanted to try switching to the d20 "Call of Cthulhu" scheme. This has a number of advantages - I think the d20 system has a genuinely better method for making skill checks, and I like how D&D-style feats help to distinguish investigators from each other (in traditional CoC, the players can end up looking similar to each other). On the other hand, the gaining of hitpoints and levels does go against the spirit of CoC, but the investigators are usually so outmatched that it doesn't matter. I also don't think the standard D&D skills translate very well to the CoC investigation model.
We played a session using the d20 rules, and they mostly worked fine. I'm not sure how to refine armor class and attack rolls in combat - essentially, the Mythos monsters can hit the investigators 60%-75% of the time, while the investigators might have only a 30%-50% chance to hit. When each hit is potentially fatal, these kinds of probabilities spell certain doom over the long run; I'll have to see what I can do to ensure survivability.
The Sanity rules are essentially identical to standard CoC, which is probably for the best - I liked the Sanity rolls more than any other part of CoC. Currently, one of the investigators in my campaign is experiencing drug addiction - always a foreseeable consequence of taking psychoactive drugs.