Doom

Tomb Raider. Eidos Interactive's 1st person attempt at Indiana Jones would have been an also ran if it hadn't been for some unknown individual deciding that the protagonist should be a woman. An unfeasibly-shaped woman, but a woman.
All the boys loved Lara Croft, because of Lara and her grunting.
All the girls loved Lara Croft, because she was Girl Power.

But we all loved Doom as well, because Doom was the first really fast first person shoot 'em up game. A gorefest of spectacular proportions (the BFG was always my favoured weapon), the blood quotient was off the scale.
Even in those 1990s blocky-graphics days it was quite possible to become utterly immersed in the game play.
So when the follow up Quake came out, with Trent Reznor's 9 inch Nails score, it quickly became the "must play" spare time hobby for IT technicians (who always had the best PCs).

Both Doom and Quake could be played over a network. It was all a bit experimental but the documentation was there and one afternoon we tried it (just as a technology proof, of course). It worked between my office and my IT technician colleagues's and in deathmatch mode we could chase each other around.
The noises were not work-friendly, and it seemed to have a deleterious effect upon the network's performance (that we blamed on a Microsoft network patch...) so we packed it in and scheduled an after-hours session.
On a dark, cold night in separate offices we set up a call between the two office extensions, left the speakerphones on, and started Doom. With the PC speakers turned up and your potential murderer cackling in your speakerphone the experience was truly immersive and very spooky, I can quite understand how people get addicted to LAN parties.
We ended the night about even and very spooked; we later learned that Lloyds' IT department tried the same expeiment but during the day and wrecked an entire day's trading. They were all fired (and I'm sure ended up working for Eidos), but we all learned a lot from Doom...