Hi, I'm Alex, author of Javelin, chiming in! d20 is indeed a free rule system and I disagree that it was created with malicious intentions, quite the contrary in fact, which is how it manages to survive to this day with products being released by the dozens each year. However, d20 - as a trademark - is a copyrighted term. There are certain weird (but understandable) limitations, regarding its use: you cannot publish a book with character generation rules; you cannot publish a book that calls itself a "core" book. and lastly and sadly, you cannot create a video game. Note however, that I said that only
the trademark is subject to these rules. You
can create a d20-system game but you
cannot advertise it as being d20-compatible. Technically, not even compliant books can use the d20 logo anymore since Wizard of the Coast has made it obsolete for D&D 3.x.
Here are several examples of this sort of thing:
- Pathfinder is a "core" rulebook with character generation rules using the d20 system. It doesn't show the d20 logo though, just "OGL compatible" http://68.media.tumblr.com/ad6943464c85 ... 1_1280.jpg
- Pathfinder itself has a couple of computer games, proving that you can create d20-system based games. Pathfinder online and Pathfinder Adventures. Both, of course, use the Pathfinder (d20/OGL) rules.
- "Core" rulebooks for alternate settings by Mongoose Publishing. You can notice here that Mongoose has d20 written all over the page, including the page address and navigation menu. As a almost 2 decade-old d20 publisher, they understand that it's all pretty much game as long as you don't print ads or book covers saying "my game is 100% D&D and d20 compatible", logos and all http://www.mongoosepublishing.com/ebook ... books.html
- A recent thread on reddit where we discuss this at some length, it has taught some stuff I didn't realize yet which I'm trying to convey here now https://www.reddit.com/r/roguelikedev/c ... ?context=3
The original d20 system is really great for achieving that classic hack-and-slash style of D&D, especially when you have a computer game doing most of the math for you. As I tell people on reddit from time to time, it's a lot of work to get it done - it's a rule-heavy system and it doesn't fit a video game as-is. There's a ton of other open systems with cool rules and such but I'm not familiar with any of them, which is why Javelin is closer to my tabletop experience. Also, unless they're really close to the original d20, like Pathfinder, then you're missing out on hundreds or possibly thousands of published, professional OGL content out there that you're free to use with your game as long as you follow the OGL and d20 trademark restrictions. Here's a comprehensive wiki listing I've edited recently on the subject
https://wiki.rpg.net/index.php/Open_Game_SystemsYes, it's a shame I can't tell people Javelin is a d20 game because of some bureaucratic details coined 20 years ago almost. It's a really big selling point for a game but I think that besides the rule system, my game hopefully has enough to offer so I can just tell people it's a "free open-source party-based strategic roguelike" and hopefully they'll be willing to try it out just as well. I'm tempted to throw in an OGL in there but let's admit it: OGL isn't as sexy as d20, people at large don't know what that means or why it's awesome.
The last post here about game rules copyright not being enforceable in a court of law, "do whatever you want", "friendship is magic" is just beyond retarded. Maybe (and that's a very big maybe) if you're a million-dollar a month company you'll be able to make your case against Hasbro (WotC's parent company) in court. If you're just a guy doing a game, you better prepare yourself for 10 years of legal fees to even try to make your point - and I honestly think that it's an argument that doesn't hold any credibility despite people repeating it over and over online. You won't get sued though if you play by the rules I've tried to outline here. I'm not qualified to give legal advice but I've read all licenses involved thoroughly and share my opinion in good faith. Lastly, I don't think Hasbro and WotC care much about anything we do with the 3e system at this point, with possibly 5e out and 6e somewhere on the horizon, as long as we play nice..
There are other d20... err, OGL roguelikes out there too in case people lurking here are interested in taking a looksie: