Favorite House Rule.
Hmm.
Well, I know my least favorite house rule. We’re playing Dungeons & Dragons and when in combat, we could only say three words per round to each other. That last sentence would take seven rounds for my character to complete. Really annoying. I suppose it was to cut down on table chatter and make combat faster or to realistically model how much one could speak in a game where an elf can summon a massive ball of fire to immolate an owl/bear hybrid. We said it was annoying, but the DM stuck to his guns.
So we had an encounter where some bandits in some bushes started shooting arrows at us and we nearly wiped them out in the first combat round, chasing two stragglers for two more rounds, which is what, nine, eighteen seconds of time in-game? So we’re chasing down the last two guys and my paladin shouts out to them, “That was a!” Next round. “Poorly planned ambush!” Everyone laughs.
Well, everyone but the guy behind the DM screen.
But favorite?
It’s probably going to be a rule that’s used in some other game, ported over to another one.
Fan Mail in Primetime Adventures — where players give rewards to other players for bringing something awesome to the table. But it’s a bit difficult to institute in some games. It’s somewhat equivalent to John Wick’s Fraternitas dice mechanic and somewhat close to Eberron’s Action Dice thing. Basically, you do something, someone rewards you with extra dice and you can use those to add on to another roll to do something. Throw a spear at a clockwork storm giant? Roll your d20, add your attack bonus, and — just to make sure — roll in that d6 Action Die someone gave you a few scenes ago.
Neat.
But the one house rule I use (or try to) in all my games is “Let It Ride”, from Burning Wheel, I think. Once you make a check in the game, it sticks around for the whole of the thing you’re doing. Because making a whole series of checks for a thing your character is doing means that failure isn’t an option, it’s an eventuality. Sneaking into a building with a 50% Sneak Ability? Roll to get past the first set of guards. Now roll to get past the second set. Now roll to see how quietly you get up the stairs. Now roll to see if you can open the door without any of the guards detecting you. — No, just roll once, or else your little burglar is going to only succeed all four of those tasks 6.25% of the time. It’s not if she’ll be caught, it’s when.