1. To fix a perceived problem with the Rules as Written
2. To make the rules fit the worldview of your campaign setting
3. To speed up play – especially in combat
4. To slow down play – for example, to add layers of detail to a skill system, or increase simulational realism
5. To put your own stamp and style on the game

Pretty sure there’s many more. I’ve known folks add House Rules that make the game less fun, and I’ve been guilty of that several times myself too – but not intentionally

> Fix the Fluff before you Fix the Stuff

I agree 100%. We’ve long explained how pre-4e D&D magic works by saying that spellcasters pre-cast their spells and only utter the final syllable to activate the spell when it’s needed. That solved that whole Vancian memorization silliness without changing a single mechanical thing. Zero house rules needed.

I like your ideas about the Elven Perception ability; our favourite suggestion so far is that all elves are actually contact lens salesmen. They don’t sell the contact lenses to other elves because that would affect their commission rate and is against company regulations. Or something.

After I hit step 1) Identify the Problem, I immediately started tearing it down hysterically. But I realized there’s most likely an easier way to do it.

In my example, I didn’t like the organization and structure of magic in the system. I wanted to redo it, but I found that the problem wasn’t crunch, it was fluff. In writing 8 pages of fluff about magic, I ended up finding a way to comfortable BS the explanation for why magic is the way it is.

My conclusion: Fix the Fluff before you Fix the Stuff.

@GreyWulf: Maybe Elves naturally commune with entities. They’re socially inept tree huggers because they can commune with living things well, and they act as a mental LAN for their party. Creating a faint “group awareness”. Or maybe Elves are so intimidating that the party pays careful attention to everything, lest the cursed elf uses the environment to do something to a party member.

In 4E, changes to skills would have to be pretty radical to create big ripples. You might shift class skills around, but that doesn’t do much because with such a small skill list there isn’t a lot of niche protection to begin with. You could change the training bonus from +5 to some other number, but that would (presumably) impact every PC and NPC equally. Even if you broke the system down so that you’re back to using skill points instead of training, feats and paths don’t depend on skills, so the change doesn’t ripple.

However, I’d probably do most of them again, or at least simplified version of them. I would, however, pass each one through my Common Sense and Knowledge (Gaming) filters.

I honestly don’t have the experience with 4E to start fiddling with the rules, but we handle the Elf’s +1 Group Perception modifier with a pretty novel approach: We usually forget all about it.

House rules tend to catagorically nerf entire swathes of character options to such a degree that it’s better to just make a new character entirely. I’m talking about crap like critical fumbles, removing AOOs..blah. If you’re going to negate entire trees of options, how about just finding a system better suited to the game?

That said, in 3.5 I did nerf a number of things, such as Save Or Die spells, Ressurection spells, and the god awful polymorphs. To be fair, these were all considered WMDs (Weapons of Mutual Destruction) by most WOTC designers in the first place…In that if the players or the DM used either, the opposite party would almost be required to respond in kind due to the dramatic shift in balance it caused.

Let’s face it- you use house rules typically to nerf something you don’t like, and usually it’s the result of someone abusing the effect. It’s a form of telling dirtbags to stop being dirtbags.

In 4e I tend to see everything as more or less balanced. Although I think Daily Fey Step is an overreaction, the general point of the eladrin is to abuse teleportation…other races DO get consummately powerful abilities (DragonBreath? Reroll Attack? Extra At Will Power…)

On the other hand, we tend to improv house rules in almost every session, because it’s usually easier to just make a call and move on than to pause the game while we look up rules.

I tend to run a lot of indie games with very general conflict resolution systems, and I find that ‘house rules” per se are very rare, since the mechanics don’t have a rule for every little thing. If you’re making the same check for any situation involving your Family (for example in Hero’s Banner), then you don’t really need to know if you get a bonus to lifting heavy objects.

For 4e D&D, we’ve just one House Rule, nerfing Eladrin’s Fey Step to being a Daily Power. Beyond that, we’re trying Really Hard to be good and play the Rules As Written We’re considering replacing the Elf’s group bonus to Perception with something else simply because we can’t rationalize how the heck that would work; for now though, it’s still in.

When it comes to House Rules overall, we find it’s better to try to understand the rules rather than re-write the bits you don’t like. It’s too easy to knee-jerk a “fix”, only to find the fix can cause snowballing problems later on – especially when the “fix” involves escalating one or more character’s relative power.

That said, at the end of the day it’s your game, and if you feel something merits changing, then make the change. If it works, more power to you