Freespace 2 comes to mind. The whole game engine was open source not just the game itself. Looks like there is still a community building on it too. https://scp.indiegames.us/

I always thought it hinted that it was the Song of Growing that the Da’shain Aiel used to sing with the Ogier and the Nym during the AOL.

1961 Gibson Discoverer Amp. Found it in the basement as a teen. Replaced the fuse holder and fuse. Powered up all the tubes no problem and still running strong today.