There’s a lot of jargon that goes along with the hobby of playing a tabletop RPG, but one term you’ll read and hear over and over again is “d20”. What the heck do these three characters mean and why has d20 become so pivotal to tabletop RPG gaming over the last two decades?

The Easy Part

Describing what d20 is isn’t very hard. It’s a rules set meant for tabletop RPG gameplay. It was originally developed as the basis of the 3rd Edition of Dungeons & Dragons. Launched in the year 2000 by Wizards of the Coast, d20 brought much-needed modernization to the rather clunky mechanics. The name “d20” comes from the 20-sided dice that’s probably the most universal symbol of tabletop gaming there is.


The Hard Part

When it comes to the details of how the d20 system works, then things get complicated quickly. That’s because it aims to solve an even more complex problem. How do you simulate a world filled with characters and interactive objects without the help of a computer? These days we are pretty used to video game RPGs that simply crunch numbers in the background to determine in real time whether your arrow hit that orc in the eye or not.

Every character in the game has a set of attributes with a corresponding score. For instance, intelligence or physical strength. A wizard might be very smart but lack brawn, as one common example. Attributes determine many things that your character can or cannot do. Some types of equipment might need certain minimum attribute levels to work properly. Actions you want your character to perform almost always depend on their attributes in some way. For example, a barbarian character is likely to have low intelligence, while a wizard is likely to have high intelligence. This means the Wizard has a much higher chance of, for example, correctly translating an ancient scroll.

Which brings us to the next element beyond simple attributes – random chance. The character’s innate attributes work as modifiers applied to a dice roll. An action, such as an accurate bow shot, will have a number known as the DC, or “difficulty class”. If shooting a bow well relies on the attribute of dexterity then the dice roll added to the character’s dexterity level has to be higher than the DC. If it is, the arrow hits where it’s meant to.

This system of dice rolls and modifiers is the core mechanic of d20 and can be applied to just about anything. Of course, there are plenty of sub-systems that relate to specific actions with modifiers of their own. The terrain or other factors might work for or against the success of a given action. This basic concept has proven to be almost infinitely flexible.

Why Was d20 so Special?

The d20 system marks a major turning point for tabletop RPGs. This was when Wizards of the Coast opened up their intellectual property so that other companies could use it to develop their own games. It spawned the “open game license” and “system reference documents”. Now anyone could create compatible games, and players didn’t have to learn a whole bunch of different RPG systems.

In other words, this is a major example of creating a standard within the tabletop gaming world. This approach to game design and industry standardization has had some pretty profound effects; not just on tabletop games, but on other types of complex games as well, especially when it comes to video games.

D20 Made the Whole Pie Bigger

Thanks to the good Wizards making d20 available to outsiders, there was a major increase in RPGs to choose from. Even Wizards itself started using the universal form of d20 to power games that weren’t Dungeons & Dragons.

For a while, d20 provoked a golden age of plenty from the perspective of fans. Unfortunately, if you wanted to be officially licensed for d20 you had to comply with rules set out by Wizards of the Coast. As the custodians of d20 they had the power to revoke licenses and set terms. After some censorship against developers that wanted to put sexual content in their game, many creators went their own way and more open-game systems were released. So even when d20 had negative press, it improved the tabletop RPG landscape for everyone.

playing dungeons and dragon

Significance to Video Games

Along with the rules sets it came from, the d20 system has had a profound effect on video game RPGs. Although these days there’s a great emphasis on physical simulation and direct skills when it comes to video game RPGs, the influence of d20 can be seen just about everywhere. Characters have attributes; items and enemies have them. There are now thousands of automatically-applied modifiers. The main difference is that things are running in real time, but the framework is still similar.

The Future of d20

While D&D itself is now on its 5th Edition, which has courted a lot of controversy, d20 will most likely keep inspiring tabletop and other RPG design for years to come. There is also now a derivative of d20 known as d20 Modern. The biggest change in d20 Modern is that the mechanics have been divorced from a fantasy setting, so you can build your adventures in any genre you would like. Basically, d20 Modern is doing what GURPS originally set out to do and, arguably, is doing a better job of it. So for now, at least, d20 is going nowhere!