Holy crap! One of my favorite all time FPS games. The single player was great (and HARD!), but what I really enjoyed was the multiplayer.
It was way ahead of it's time. You could uniquely customize your character so no one looked the same when you played a match.
It had so many cool game modes that were criminal variants of classic modes. One of them, as I remember, was a CTF variant where both teams had to collect money that was falling from the sky in the center of the map, and bring it back to your gang's safe. If someone was killed while carrying money, they dropped it, and anyone else could pick it up. So you had to have people grabbing money, and people escorting them. However you also needed someone to guard your safe because the opposing team could get into your gang's hideout and steal money from the safe.
The weapons were great. The best implementation of a flamethrower in multiplayer EVER!
Flamethrower in action:
https://youtu.be/lU-0qkTgifI
"I want AI to do my laundry and dishes so that I can do art and writing, not for AI to do my art and writing so that I can do my laundry and dishes."
- Joanna Maciejewska