Quake is a First Person Shooter by id software created in 1996. It's the successor to Classical Doom, and was the first fully 3D FPS.
Digging abit into that Portable Audio Quake it seems to behave rather... odd, compared to traditional quake. When hitting S it seems to auto dump you into a multiplayer deathmatch server, which in itself is pretty interesting, but not so great if you want singleplayer. Console map shift commands also don't quite seem to do it, but I think you can brute force the offline singleplayer by pulling up the singleplayer menu in the console.
You can find a list of the console commands [here], though zquake might behave a bit differently for some of them. If you want to play the singleplayer campaign, open the console, the hotkey is typically the Tilde key, then type "menu_singleplayer", and hit enter. This drops you into the difficulty selection area, from here you can choose the difficulty by picking left easy path, middle, or right hard path, then one of the 4 campaigns by walking into a teleporter.
Alternatively you can use the map warp commands in the console, such as "map e1m1", "E" meaning episode, and "M" meaning mission, there being 4 episodes. Changing the map without hitting into singleplayer still seemed to lock into a multiplayer server though. Ah, one more thing, saving and loading through the console seemed to cause problems when loading a saved game. You can open the singleplayer menu again with "menu_singleplayer", this menu has 3 options, New Game, Load, and Save, so you can select save and just hit enter to save in that slot, same with load.
: Accessible Paint Tool
: Accessible 3D Model Viewer