Saturday, June 29, 2013

DCC RPG, Charts, and the Pareto Principle

A recent post on Tenkar's Tavern has me thinking about why I object to the Dungeon Crawl Classics RPG's use of charts for each magical spell. Given that I love charts, it comes down to a statistic sometimes called the Pareto principle.

According to Pareto, 20% of causes are responsible for 80% of the effects in a given system. This is an interesting general rule that has some broad applicability. Here I want to apply it to RPGs and specifically to random tables. Specifically: in an ideal RPG design, 80% of the time I'm referencing charts, it should be to a core 20% or less of the charts in the game system. For instance, I don't mind referring to a combat chart, the experience table, a wandering monster chart, or the turning undead chart - they are all core activities. I'm able to optimize my access, whether it's through memorizing the charts, or knowing where they are, or having copies or a GM screen.

DCC's spells break that efficiency, because you're stuck referring to them every time the spell is cast. People wind up playing where spellcasters have "spellbooks" with photocopies of the spells they're actually casting. Because everything's a fairly long description, it's a pain to memorize them; you probably have to look back at the chart every time.

They're also not useful in the sense that each chart applies to only one spell. This is a poor contrast to, say, Spellcraft & Swordplay's spell retention table, or one of the better touches in 2e AD&D, the Wild Surge chart in Tome of Magic. Even critical hit charts have better ability to be spread across multiple uses than spell charts that literally affect only a single spell.

If we apply the Pareto principle to gaming, 80% of charts should be things that are not referenced during play. These can be as particular and picky as you like - stuff like dungeon dressing, monster creation, magic item customization, and other "off-screen" details. The 20% of charts designed for play-time reference should be lean, mean, and memorable. You don't need to master the potion miscibility table, but you should have an understanding of the basic combat table that makes it easy for you to adjudicate it quickly. DCC is forced to virtually the opposite - 80% of charts used are one-off things, rather than the clever high-usage ones it does have such as the "turn over the body" chart.

This rule of thumb, I think, is a good guideline for making reference charts for RPGs. Most should be aimed at the prep time, and those should feel free to be as intricate as you like. Only a minority should be true "everyday" charts, and these are the ones that need optimization so they can be both interesting and have results that can be memorized.


  1. I Paretocize spell mishaps by having them be randomly failures, wrong target or wrong spell.


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