The Quake community regularly performs map jams. While I haven’t tracked the efforts of the previous ones, this jam results in a large, nonsequential set of maps on offer, combined with a full conversion that creates new enemy variants, and remixes Quake’s known weapons into new forms (dual nailguns, a rebar cannon, a multi-missile launcher, and a gemstone that functions like Doom 3’s soul cube).
When you load in, you’re brought to a museum-like “gallery” with portals into each of the maps created for the jam, denoting their author and difficulty level; sorted into “main offerings”, “new faces”, and other sections.
The simplest way to set the mod up is as a mod for Quake (though ironically, you’ll be replacing both the main paks, AND the engine)