As far as I know some D&D core books:SRD,DMG,PHB and MM are free. (If I 'm wrong plz tell me). So I want to know for what kind of licence Troika or Bioware bought from WOTC to create they games? May be core books are free only for reading, but not for using in computer games? Or may be they paid not for core books, but for modules and items?
Look here in the section titled "Official Open Gaming License FAQs". Basically there are restrictions on what (and how) you use open gaming content in computer programs. Hope that helps.
What Hazelnut said. Right now, only Atari (Ex-Infogrames) has the right to release D&D related computer games. *sigh*
Ah.... it is not good... And if I create own system based on d20, can I make and release game based on it?
Erm, if you have a good lawyer maybe as Atari can't really afford a big legal battle unless they are certain to win. Better to take either a totally open source system or create your own though.
