Quake 3 is a first person shooter, not based on any realistic situations or places, set in the future in so many arenas.

Quake 3 was a huge advancement form Quake 2 in terms of how the game is played, the weaponry and the graphics.
Firstly the Game is not set out in missions it is like Unreal Tournament, it just has games where you have to massacre the other people on the level and work you way up the chard of levels. This gives you a very good base for multiplayer playing on the net.
The graphics are some of the best yet from this type of game, it brings a whole new reality to the experience of playing the game although to run it at max resolution you will need a very good and up to date graphics card. The weaponry has been updated once again from the Quake 2 weaponry but the weapons have been upgraded and some changed.

the weapons in the game:

Machine Gun
Rocket Launcher
Plazma Gun
Rail Gun
Grenade Launcher
Shot Gun
BFG

The game play is exelent and there are 5 different skill levels to choose form that you can work up as you become a better player. All in all a very good game.