It is a truth universally acknowledged that you could write a better system than what’s in this ridiculous rule book.

The point at which someone stops being a New GM is when they start trying to make their own rules system. Whether a hack of an existing system or making something completely new, crafting the rules you want for yourself is a rite of passage every TTRPG player should go through.

Sometimes, this is good. Many times, this leads to horrible things.

Chesterson’s Fence

In the matter of reforming things, as distinct from deforming them, there is one plain and simple principle; a principle which will probably be called a paradox. There exists in such a case a certain institution or law; let us say, for the sake of simplicity, a fence or gate erected across a road. The more modern type of reformer goes gaily up to it and says, “I don’t see the use of this; let us clear it away.” To which the more intelligent type of reformer will do well to answer: “If you don’t see the use of it, I certainly won’t let you clear it away. Go away and think. Then, when you can come back and tell me that you do see the use of it, I may allow you to destroy it.”

from Wikipedia

To paraphrase, unless you know why the rules work the way they do, changing them is going to lead to unfortunate consequences.

I know this from both sides. I have absolutely made bonkers-broken characters out of spite to prove to a GameMaster their changes were flawed, monstrosities which I dare not name that created party imbalances only smoothed over via Spotlight Balance.

And, in turn, I have tried to make systems better by revamping the rules. This has almost always been a mistake, because of one simple problem.

The Rulebook

If the rules are bad, but easy to reference, then play can continue. Maybe less satisfyingly, maybe an ad-hoc adjudication needs to occur, but flow isn’t broken.

Updating the rulebook is essentially adding a second, required rulebook to the game. Which means every player will need to learn a second rulebook, creating more steps to play.

Except the second rulebook contradicts the first. Which means players need to memorise both books. And when a rules question happens, players must reference the added text, then the core text, and then very possibly still not have an answer.

The goal of rules is to resolve conflict fairly, with as little friction as possible. While creating an additional rules supplement may make the conflict resolution more fair, inevitably the added friction will slow down game play. Almost all players are looking to play the game, not read reference books.

And that’s without considering the social effects.

The Ego

Players can dunk on a rulebook and not feel bad. Hell, after years of running and loving World of Darkness, I will still shake my head at Page XX. Bad rules can build a kind of camaraderie, because everyone’s in the thick of the non-existent index together, and you can all laugh about it together.

Contrast this with GM customised rules failing. Suddenly, no one makes eye contact. Players wonder whether they should bring up whether the rules aren’t working, or introduce balance issues. No one wants to say anything, and the enthusiasm for the game slowly slides downhill until people stop showing up to game regularly.

The Results

Heavily customised rules create friction and table tension that can be hard to manage. It’s not for the feint of heart, and should come with a huge Session 0 disclaimer that play-testing new rules will be a part of play. By default, stick to the core terrible rules, because the only thing worse than a bad system is a bad customised system no one quite knows how to get working.

My personal rule of thumb is to limit House Rules to Five. You can change five rules, total, with the customisation descriptions limited to a single sheet of paper. Period. And all five slots should not be used up in character creation, because then you don’t have an open slot for issues that come up during play.

If the system needs more than five house rules… get a better system. Seriously, there’s lots of them. Be nice to yourself. Have nice things. Like coherent rules.