Saw this proposed house rule in the Swords & Wizardry forums:
Save vs. Wandering Monsters
Instead of rolling a 6-sider every now and then, I’m going to ask one of the PC’s to make a saving throw (vs. “wandering monsters”) whenever the party is being especially loud, incautious or is simply wasting time. A failure means the party’s recklessness has caught the attention of wandering monsters (think of the Hobbits dropping the pebble down the shaft in Moria). I like the idea of this rule because it puts the fate more in the players’ hands, but I’ll have to see how it works in practice.
Another poster notes that using a standard saving throw means that higher-level PCs have less of a chance to attract wandering monsters due to improved saving throws. I can see how that might make sense, if you simply assume that more seasoned adventurers just know to be a bit quieter even when making noise. But a 9th level PC banging a gong (for instance) makes just as much noise as a 1st leveler doing the same thing.
The original poster responded that perhaps a negative modifier equal to the dungeon depth would fix that problem, and I think that’s reasonable.
What I’ve generally done (though I’ve never codified it or even thought of it as a “house rule”) is to simply roll an extra wandering monster check any time I think the PCs have done something to possibly attract unwanted attention. Sometimes it’s just another roll like the hourly standard check or whatever is specified for that area, and sometimes it’s an x in 6 chance to alert monsters in a nearby encounter area.
PCs can’t get a heavy door open and want to chop through it? Fine. It will take d6+1 rounds with a 2-in-6 chance each round of attracting the goblins from room #17. Or whatever I think is appropriate.
What I do like about the original idea, however, is having the players make the roll. Dropped a pebble down the shaft in Moria? Fine. Pippin’s player rolls the check. If a one comes up, everyone can get mad at Pippin’s player, which helps build what I like to call “mood”.
The only problem I can see is that this method means the players know (or can figure out) that they’ve attracted something. Maybe I want the goblins to sneak up and set an ambush. Of course, seeing a ‘1’ rolled maybe makes the players think, “boy…that can’t be good” which might be what PCs suddenly realize after chopping at the door and helps build the “mood”.
So I’m going to give this approach a try.