This is the coolest game, it's hard to not love just how much fun this is. The gameplay in this is damn near perfect: the guns all feel and sound amazing, very punchy. The way your bullets make such visible impact on enemies and the environment is mesmerizing every time. When you spray with an automatic weapon or one of the heaviest sounding shotguns ever and dust and debris fly all over the place (especially in slow motion), you'll feel like a million bucks.
The enemy AI is still somehow better than a lot of FPS games nowadays still. It's insane this came out in 2005 because it's impressive even nowadays. My only real complaint is the game just isn't really scary. Unless you think little girls with long hair are scary i guess. Besides that, It's very hard to come up with anything negative to say. Play this game, it's one of the best FPS games ever made.