Wizards Legalese OGL?

[smetzger]

That's easy, you simply write a library of OGL functions. Make that library open for anyone to use freely. If ABSOLUTELY necessary, you could release the library as open source, I suppose. But either way, the main game code stays proprietary. It's really very simple.

Easier to say than to actually do. Remember words like HP, HD, AC, Feat, Ranger, etc are open content. That means you cannot make them closed content. There are other less obvious difficulties. As far as I know I am the only one who has released a binary executable that is OGC.