id Software has released the source code from its 2004 hit Doom 3.
Todd Hollenshead, president of id Software, made the announcement via his Twitter feed last night.
The source code was ready for release at the start of November, but there was a problem getting clearance from Bethesda's lawyers.
The sticking point was a shadow stenciling technique discovered independently by id co-founder John Carmack in 1997. Sometimes known as "Carmack's reverse", the technique was separately patented by Creative Labs in 2002.
However, rather than wait for the legalities to be ironed out, Carmack choose to rewrite the offending code instead.
The Doom 3 source code is currently available from GitHub.