Hey, so I keep seeing people confused about the Open Game License. My Open Gaming for Dummies article helps dispel some of that but let’s come out and get one thing clear – it’s not “just for D&D” or just d20-derived games. Open gaming is strong and diverse.
The OGL is just a license. It’s like the open source Apache, GPL, or MIT licenses in that it can be applied by anyone – though it was written by WotC originally, it’s not owned by them and has no relation to what games can be released under it.
Guess what all game systems are open under the OGL license?
- The Action! system (from Gold Rush Games)
- Traveller (Mongoose’s version)
- Runequest (Mongoose’s version)
- The d6 system (from West End Games’ Star Wars and Ghostbusters)
- Fudge and its newer more popular variant FATE and derivatives thereof, like ICONS
And many more, including many many d20 variants from Anime d20 to Mutants & Masterminds. I’m not sure there’s a comprehensive list – here’s a couple that are old and out of date. But that’s like, a big share of the systems people have played over the decades.
And of course this doesn’t mention other open games published under other licenses, like Eclipse Phase is published under Creative Commons.
Really, publishers, is there a reason NOT to open license your system? Because face it, your system kinda sucks. They all do. Your best bet is to get it in the hands of as many people as possible so they’ll get interested and buy your products. If GURPS got open licensed, for example, maybe someone under 30 would play it.
Geek Related 
Brilliant!
I love the OGL. However I will give one reason a publixher should not.
Poor WOTC found the danger of the OGL, because they released a substandard game that split the market. The players that liked 3.5 stuck with it, and if they wanted support they went to PATHFINDER in droves. That KILLED WOTC’s market share.
Lets say OGL was not released and 4e still came out when it did. All variables being the same, I would guess 50% of the people that did not want to play 4e would have jumped back into the fold and given in. However the OGL allowed Pathfinder so those people had another place to spend their money.
The OGL was great and innovative. But if a publisher later wants to command the market share, THEN it is a bad idea.
Keep in mind I say this with all amusement, as the last D&D product I bought was the first 4e release in 2008. I am GLAD that WOTC has lost market share.
“it’s not owned by them and has no relation to what games can be released under it.”
The very first line of the OGL states that the text is copyrighted by them. I’m not sure how you defined “owned by them”, but if they are the sole copyright owners, then they can in fact ask you to stop using their license text, which would effectively neuter the license. I don’t seriously think they would do this, but it’s still a surprising statement that you made. The OGL is owned by WotC.
Incorrect; read the OGL FAQ (http://www.wizards.com/default.asp?x=d20/oglfaq/20040123f). No one else can change the license but the license itself allows free and unlimited redistribution, so they have no legal recourse to “put the genie back in the box” (if they did, they would have already).