The Specialists is an action mod created by Filippo "Morfeo" De Luca and Lorenzo "John_Matrix" Pasini, built on by a strong willed community and the first multiplayer game ever featuring slowmotion. The standards of the First Person Shooter still apply but are augmented by an intuitive stunt system, slow motion action, hand to hand combat and an array of melee weapons, customizable firearms, particle effects and the ability to play from a third-person camera.
From the time you first play it, you realize how cool this mod is. Has awesome keyboard features (slide, kung fu, high jump), lots of weapons, fun maps and play modes (last man standing, "the one"). Even play it with bots is cool. The characters for the player are nice and resembles a weapon specialist, to the extent that you would feel like a charachter of an action movie. Though, I think playing multiplayer is the real deal, I don't know how difficult is find a server these days.