Hands down one of the best games ever made for the PC.
Quake II brought with it a revolutionary new method of game play that just surpassed all of the other games on the market. The graphics were great, even by todays standard, the sound was superb, the game play was so addictive that many employers of the time had to deal with an epidemic of workers calling in sick.
The multiplayer aspect of the game was just beyond words. It squarely falls into the Oh My God catagory. Co-Op play and death match set the standard of thrill ride to new levels of high. Playing QUAKE II was one of the best experiences of my life. I would tell my girl friend of the time to take my credit cards and go shopping just so that I could have the house to myself to play death match with my friends.
Even today I still have QUAKE II on three PC's. I play the game with my nephews all the time and they are dirtly little cheaters.... shooting me in the back to get access to the goodies during a co-op game. They love the game as much as we do, and that says a lot about how well the game has endured over the years.
Simply put, Quake II is a gold metal game twice over.