https://en.wikipedia.org/wiki/Rogue_(video_game)#At_UC_Berkeley https://en.wikipedia.org/wiki/Rogue_(video_game)#At_UC_Berke... Rogue has been under a BSD lice

https://en.wikipedia.org/wiki/Rogue_(video_game)#At_UC_Berkeley https://en.wikipedia.org/wiki/Rogue_(video_game)#At_UC_Berke... Rogue has been under a BSD license since 1986, so Nethack’s predecessor is also F/OSS.