Star Wars Battlefront (2004) is the first installment in the SW Battlefront series. It featured 17 maps that players could play through. Notable maps include: Cloud City (both maps), Geonosis, Rhen Var: Citadel, Tatooine (both maps), and Kashyyyk: Docks.
It also included a galactic conquest mode where a player could choose one of 4 factions and attempt to conquer the galaxy.
Finally, there was a campaign mode that allowed players to experience 16 battles that either happened, or could have happened canonically.
There is still an active community around Star Wars Battlefront, however the online play is fraught with hacks and players who have found a way to mod their characters in an unfair way.
There are legal mods to Star Wars Battlefront, as well as map makers that were released by Pandemic Studios (the Game Developer).
Overall, Star Wars Battlefront is an amazing game, and easily one of the very best Star Wars games ever released, and I would classify it as one of the best FPS games ever created.