Half-life death match.
We played that pretty much every day in lan at the end of the work day. One of us even made a level of the office we worked in. The energy weapon was awesome, you could shoot it at the ground and it would make you fly up into the air to land on the roof of the building. Or you could use it to shoot people through a book case or wall. Laser tripwires were also a favorite to create huge chained booby traps. Stick one on a door or a hatch at the end of a chain to set of the carnage when someone gets close.
The game remembered a lot of the carnage, just after 10 minutes the office was turned into a bloody mess with bullet holes everywhere. There were tons of mods and custom levels. We were running around as anything from homer simpson with a rocket launcher to a giant tube of toothpaste with a crowbar.
It was much more fun to play multiplayer games in the same room, online fps games have never been able to match that.
We also played duke nukem 3D, quake and unreal tournament, but half-life got by far the most time.







