Designing Easy-To-Modify Games

July 8, 2014

One thing that’s pretty interesting is the level to which tabletop RPGs expect the groups playing them to hack and change them.  There’s pretty much three ways to address that, and it’s worth considering how those work:

“Design it yourself” (AKA anti-design)

This would be “Rule 0” or “if you don’t like these rules, make up your own”.  This has been in rpgs for decades, and specifically is a non-helpful way to do things.  It also gets used a lot as a defense when the rules didn’t do what they’d claim they were supposed to do.

I’ve heard arguments in the past “no, no, really the game was made poorly to FORCE you to become a better gamer”… which… is ridiculous.  You might make that argument about certain forms of training and the need to ramp up difficulty, but in games?  Difficulty should be about a challenge factor in playing the game, not a challenge to making the game work – the challenge in basketball is playing basketball, not tying people’s legs together and blindfolding them and giving them a half-flat ball.


This is pretty much the easiest way to make an easy-to-hack game, though the changes are all effectively superficial.  The Pool, HeroQuest, octaNe, Universalis, Fudge, FATE…  all of these games have easy to swap labels while keeping the mechanics identical.  What’s the difference between a heavy armored robot and a small fast robot?  The labels “Heavy” “Armored” vs. “Small” “Fast” applied to them.

On the other hand, while this allows easy genre and element swapping, it doesn’t actually make for any mechanical differences in hacking by itself.  Often these systems use a universal resolution and there’s not a lot more to hang on it.

Unified Principles

Vincent Baker has a nifty chart about how rules work vs. how we actually play at the table. (you should read the whole post, it’s almost 9 years old but still very relevant).

This is an idealized design-to-play set up.  The turquoise is the actual rules in the game book/text.  You’ll notice it’s like 98% within the other circle – which is “how we play at the table”.  In other words, nearly all of the rules or advice in the book are actually useful in play.   You’ll notice of “How We Actually Play”, the part that isn’t covered by the game text circle, is broken into two sections – Ad Hoc decisions, and Principled Decisions.

Principled decisions are the choices you make because they fit in with the principles the game has communicated to you on how things generally work in the game.

Say you’re playing D&D and there’s a gas explosion in a mine.  “Oh gee, the book doesn’t have rules for that… but it’s a LOT LIKE a Fireball or Dragon’s Breath.  Let’s say it does this much damage and you make a Saving Throw for half damage”.   You can make that call and it works with the game because it’s based on common principles within the game.

So part of a game design is how well you communicate the principles of your game – which doesn’t have to be pages of theory and designer notes, but it does need to be consistent across your rules.

Hacking a game and considerations

So, from the other side of this, as a gamer, it’s worth looking at what you need to consider when hacking a game, which then shapes things people should think about when we’re talking about game design for modification.


How much does modding the game risk throwing things way out of wack?  Some games are pretty open to tossing stuff in without too much trouble.  Some games are an exacting system of currency and bumping it around breaks things quickly.  If you are designing a game with the intent for people to modify it, you need to try to aim for less fragility and be clear about which parts are more/less able to be fiddled with before breaking.


How much effort does it take for me to hack things into your game?  Is it a few minutes or nearly hours of trying to put together numbers?  Less crunch makes easier hacking.

Complex Combinations

How many OTHER rules do I have to think about this hack intersecting with?  Are there ways it could do things very different than what I intend because of a complex interaction?

Existing Tools

What’s already in the game as rules that I could use right now or with the most minimal changes?  Why should I use one as opposed to another?  (Example: when should you make this an attribute roll vs. when should you make it a skill roll?)


What are general goals of the rules?  What are rules they follow over and over?  What sorts of things work against this?

So, here’s an example: Apocalypse World has a principle in the rules of “Soft Moves” vs. “Hard Moves”.  A Soft Move is something the GM does that warns about trouble coming, a hazard or a threat.  A Hard Move is something the GM does that has consequences, now and lasting – whether that’s injury, an NPC getting killed, etc.   A core principle is that you have to give warning, you have to go through at least one Soft Move and give the players a chance to act, before jumping into Hard Moves.

Because this is generally a good principle for a lot of action games (forewarn danger, then enact danger) as opposed to “gotcha!” traps, it is something people caught on to and find AW very hack-able to many other things (Monsterhearts, Dungeon World, etc.).

On the flipside, the D20 flood of bad materials is a pretty good example of what happens when you have both high complex combinations and little in the way of principles communicated.


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