[Anaraxes]

When I was a kid, we invented some RPG-style combat rules for "Combat Clue", which allowed you to use all those murder weapons scattered around the board on other characters. You could win the game by figuring out who the murder was, as usual -- or if you were the murderer, or just suspected you were a murder, or were jealous of someone getting too far ahead in figuring out the killer, you could try to kill off the other characters with the candlestick, rope, etc. And of course once someone fingered you as the original murderer, you had nothing to lose by trying to get the detective before they can turn you in, as they can only hang you once.

Hidden movement rules with a GM. Beware of line-of-sight, as if someone could see you attack another character, you'd also be guilty and could be turned over to the police-- if any of the witness survived, of course. Using the pistol let everyone in the mansion know someone was being attacked (and someone was doing some attacking) when suddenly, a shot rang out, but at least it was a ranged weapon, so you could shoot people trying to run away down the halls without having to get next to them or chase them around corners into who-knows-what. Last pawn standing was the automatic victor, fingering whoever they liked as the killer(s) responsible for all the deaths. Or a remaining group of peaceful people could just let someone ID the original killer (alive or not).

The hardcore version keeps the standard rule that lets you summon people to your room when you make an accusation. Being in a room by yourself is both dangerous and suspicious. Travel in packs.