I'm sorry, could somebody please tell me? What's so special about the D20 system?

You want a random number between 1 and 20, you roll a twenty-sided die (damn, I left mine at home!) - next you'll be telling me you can't use six-sided dice either?

I take it I'm missing something here, right? Is there something special about the d20 system, aside from the pretty 20-sided dice?

(This isn't intended as flame against anybody - I really wish to know what's so special about this fabled system!)

"d20 System" is a Wizards of the Coast trademark, and the name of a vaguely generic role-playing system, including the use of a d20 to resolve skill checks etc, but also almost every other detail of a pRPG (major omissions include character creation and advancement rules)

The actual act of rolling a d20 to generate a random number is only a very small portion of the d20 System, and could reasonably be (and historically has been) employed in any number of other systems.

Remember, rules are not intellectual property. No-one can copyright the idea that when one person has a score of 12 and the other person has a score of 4, scoring 16 or above when you pick a random number out of 20 means that the first person succeeds in doing something to the second one. If you want to use that particular statistical resolution in your game, nobody can stop you.

The license refers to being able to use the d20 term as a promotional tool, but has nothing to do with whether you use the statistical laws underlying their rules, which are not protectable. In a similar way, you can't go saying that your software is "Certified for Windows" unless Microsoft say so, although you are totally able to create and distribute Windows-based software without their say-so.

Having said all that, developing your own system is not all that hard, and doesn't take hundreds of hours of testing if you apply some simple knowledge of statistics and probability to it.

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Original post by Kylotan Remember, rules are not intellectual property. No-one can copyright the idea that when one person has a score of 12 and the other person has a score of 4, scoring 16 or above when you pick a random number out of 20 means that the first person succeeds in doing something to the second one. If you want to use that particular statistical resolution in your game, nobody can stop you.

I could be wrong here, but I think Magic: The Gathering managed to patent its game rules. So I think it's possible to protect even something like rules.

But they're really the exception and not the rule. I agree with Kylotan, d20 doesn't own the idea of a 20 sided dice, and the ways it can be implemented.

And in the end, its an issue of how strongly d20 protects its name and ideas, and the amount of light your game recieves. Some companies may not care that an indie game used some of its concepts when the people who made it are still living at home with their parents. [lol]

Where does it say that you can't make a computer game? I was reading the OGL, and a few other open licenses, and didn't see anything about it. Most allow derivative works, which would include a computer game.

That said, you still can't use anyone's trademarks or copyrighted materials without their permission. So as far as I can tell you can create a d20 compatible ruleset, and use the d20 and OGL logos under the OGL license. You just can't use any of WoTC's d20 systems with trademarked names.

Numsgil: WoTC patented the concept of "tapping" a card, which means turning it 90 degrees to show that it has been used this turn. This pretty much killed the card game market, since all the small players had to pay WoTC for the patent...or pay their lawyers.

edit: Whoops, I take it back about making a computer game. It's in their "d20 SYSTEM TRADEMARK GUIDE VERSION 5.0". So, you cannot use the logo, because it's WoTC's trademark, and they do not allow "Interactive Games". You can still use a d20 compatible ruleset for your game mechanics though.

Their software FAQ explains this far better than I can:
http://www.wizards.com/default.asp?x=d20/oglfaq/20040123i

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Original post by Numsgil I could be wrong here, but I think Magic: The Gathering managed to patent its game rules. So I think it's possible to protect even something like rules.

I don't know the whole story, but I think WotC just trademarked the terms used to refer to certain rules. Thus, if your card game has the players turing a card on its side to indicate that it has been used, you cannot refer to that as "tapping" the card.

I would endorse the usage of the old Star Wars RPG system... I don't know if it's usable now that they've abandoned it for the D20 system, but the Star Wars RPG had an INCREDIBLE system based on D6, back when West Coast Games owned the rights to it. WoTC bought them out, and killed the D6 system.

Anyways, since its not being used anymore, I wonder if it would be possible to use it without people complaining?

I can't say for certain until I find the patent statement somewhere, but according to several sources on the magic: the gathering site, "the company holds an exclusive patent on the play mechanic of trading card games."

That sounds an aweful lot like more than just 'tapping=turn 90 degrees and is used'. They OWN the very IDEAS, so it is possible for a group to own intellectual rights in the form of patents, if not copyrights.

I think their trademarks are the names and symbols used in the game. And I difinately KNOW that Magic: the Gathering guards its patent and trademark rights heavily. So anyone trying to base something on magic should tread very lightly if they plan to distribute something to more people than just their close friends.

Since d20 is from the same company, I would tread lightly on this issue as well. I doubt they have patented the d20 ruleset too, but its always better to err on teh side of caution in these matters.

Well this all links in well with one of the threadsd in the writing forum about "Big Evil Corporations" :(

My (very vague) understanding is that:



You can use the d20 ruleset under the OGL provided you follow the terms of the license (which seem to be that anyone who wants can use what you produce in any way they see fit provided they also allow others to use what they produce, etc, with everyone along the chain remaining bound by the same license)



You can use the d20 rules and the d20 logo provided you don't give anyone enough information to be able to play without the D&D core rulebooks (specifically, how to make skill checks or generate or advance characters)



You can use something functionally nearly identical to the D&D rules, provided you have good enough lawyers to argue that you didn't crib your system directly from their rulebooks...





In any case, you'd be advised to consult a real lawyer before doing anything too like cribbing the d20 rules.