What can i say?
Theres no doubt about it, that ID are the kings of the FPS genre, Inspiring modern day FPS such as counter-strike, Half life, CoD (Run on the quake III engine i might add) and other titles.
Where to start,
Well, this game was made to be the ultiamte experience in online FPS gaming, and it is, I have spend hundreds of hours playing this game for a long time, and it never gets old.
Compaired to more modern FPS, such as CS were 10mins im bored outa my head for camping etc, Quake offers the fastest gameplay available.
There are many player made mods for online play, Including Instagib, Defrag and my personal favourite freeze rails.
Single player is lacking, but that was never the intension for quake III, if you want a single player game in this genre go check quake, quake 2 and doom.
Defiantly the best online FPS currently available.