Map Jam, the Quake mapping get together when anyone and everyone maps out the theme, released their Map Jam 6 map pack. The theme this mapping session was (as the title suggests) Fire and Brimstone. Thirteen mappers participated and released a variety of maps. All single player so you gaming loners (like me) can have a blast!
It's recommended (highly) that you use the Quakespasm engine for this bunch of maps as it's the only engine tested that had no issues running every single one of them.
You can download the map over at Quaketastic and can get the Quakespasm engine over at Sourceforge (note: Sourceforge has been re-working some installers you download from it's site to add extra downloads, if you download the engine and it tries to install something else it has nothing to do with the Quakespasm engine developers).