Thanks a bunch, that’s a nice selection of options. I’ve tried QuakeSpasm and Spiked, they seem to require original game files. Where do I get them or do I have to buy the game on Steam? AFAIK, original source files are freeware and don’t need to be purchased. I don’t intend to play the original game anyway, have completed it countless times. I’m more interested in custom maps.
The original game data files (id1\pak0.pak and id1\pak1.pak) are absolutely required to run any of these, because even for mods these files have base assets. And no, they are not freeware - one has to buy the game. Usually people buy Quake on Steam or GOG.