Pan Quake is a Source port hack made by Aardappel. Most significant feature it holds surely its "Panorama mode", which will allow player to see 360 degree around by stitching the visuals together and creating one big field of view. Without panorama mode active, Pan Quake will act like GLQuake.
Its field of view capabilities only limited to player's cpu power, Pan Quake goes heavy on the system sources when trying to give player a large field of view with better graphics, and that reflects to frame rate. Player should adjust the configuration to balance between frame performance and field of view.