@zarfeblong @matt source being findable isn't the same as Open Source. Open Source means you can legally remix and legally sell or give away your new version.
You still can't ship a game called "Zork" (trademarks are still protected), but Open Source means the game and story can be repurposed in whatever way you want...and it means it can live forever, even if the owners of the IP decide it's not worth keeping available and playable on current hardware (which has happened a few times).