I got Unreal Tournament at the same time I got Quake III Arena as christmas presents. Because I was a fan and an élite at the original Quake, I played Quake III Arena first. I hated it - too far from the original, and far to difficult to get into. The worst thing about Quake III Arena is that it is multiplayer only. No mission, just shoot the computer bots as many times as you can!
This put me off Unreal Tournament slightly, but once I started playing, I couldn't stop. The engine is revolutionary, and for a multiplayer-based game, it was put together 100% correct! At first, you have to complete three deathmatches, but once you complete those, you move on to things like Domination (Command as many sectors of the map as possible, while preventing the opposing team from taking them over, and vice versa. Fairly original), Capture the Flag (Very common in 3D multiplayer games, get to the enemy base, take the flag, and get back to your home base, while preventing the opposing team from doing the same thing), and Assault (Single-player based with an attacking team and a defending team)
The best thing - very original and awesome weapons. My fave is the Redeemer, but I'm not going to tell you what it does. See it for yourself.
GET IT! NO OTHER GAME WILL MAKE THIS ONE INFERIOR FOR A LONG LONG TIME!