QuakeCon at Home 2020 was held this past weekend. During the event, Bethesda tried to raise some money for charity, and after reaching certain milestones they gave away Quake games for free.
Now it has been revealed on Twitter that the $20k limit has been reached, and the first three Quake games will be available for free via the Bethesda.net Launcher. You can download the launcher right here.
"We reached $20k in donations to charity thanks to you! Quake III will now be free in the https://Bethesda.net Launcher following #QuakeCon at Home."
So now you have no reason NOT to play these classics if you still haven't tried them. The original Quake was released in 1996, Quake II in 1997, and Quake III Arena in 1999.