Anybody played The Hidden? It's a mod for Half Life 2. It's pretty good.

Basically, one person plays as this guy who's been experimented on, and he has these special abilities (as side effects of the experiments) so that he is almost invisible, and moves very fast. He can also grip on to walls and ceilings and jump from them on to other places.

Then there is everybody else on the server, who gets armed up with some nice weapons, either some machine guns, a shotgun or a particle launcher, with a sidearm, and a little extra like a laser guide or a flashlight, or nightvision. They're on a mission to hunt down this crazed psychotic experiment man! It's very very hard and very very challenging, as he is almost silent and you'll hear him breathe at the last minute as he drives a knife in to your back!!

One disadvantage to the game is that too much time is spent dead if you get killed by The Hidden, matches generally last 6 minutes so dying in the first minute means waiting an additional 5. Though it's fun to watch people get slaughtered, the novelty wears off :/

Oh, and if you kill The Hidden, you can be him!

I know of this, but sadly it's multiplayer only, and HL2 won't work on a 98 PC with 128mb ram and a 16mb Savage 4 Pro Graphics card.

And it would eat half my hard drive.