Blast Chamber is a mod for Quake 2 by WireHead Studios.

Whereas in a normal Quake 2 deathmatch everyone just wanders around around killing each other to gain frags, with the person with the most frags wins, Blast Chamber introduces an brilliant twist. Somewhere, hidden in the level in a Blast Key, which, when taken to the Blast Computer will activate a nuclear detonation 10 seconds later. Your only hope of surviving the explosion is to rush into the small Blast Chamber, which is a safe place in the map. Anyone not in the Blast Chamber after ten seconds dies, and the person who brought the Blast Key in receives a frag.

The really nifty part is, of course, the Blast Chamber. Everyone playing is obviously scrambling to the Blast Chamber as the seconds tick away, and once they are there, they are not simply going to let everyone come in unhindered. Needless to say, the Blast Chamber turns into a charring, smoky pit of death and destruction very shortly. And what is really great is that no spawn points are in the Blast Chamber (usually), so if the person who detonated the blast kills someone just before the clock runs out, the opponent will spawn outside and be killed again!

There is a mod recently available for Quake III as well, aptly named Blast Arena.

The Story of The Best Blast Chamber Map Ever (q2dormblast)

After playing this mod for a very long time, I got the idea, as many students often do, that "Hey, my dorm would make a great quake map!" Thus began a journey which would take up much of my senior year of high school.

The planning was genius. Our dorms were designed as a three-story building, with an extremely large Great Hall in the middle, and then split in two parts on either side (one for each sex), each with three floors. Also, there was a large basement under the dorms that I thought would make a really great Blast Chamber. I put the Blast Computer in the lobby of the third floor of the girls' side, and hid the Blast Keys in the bathrooms.

The best part is that the only way to get from the third floor of the girls' side to the basement in time was to jump off the balcony, giving yourself incredible amounts of damage, and leaving yourself very vulnerable the evil railguns of your fellow classmates. If you were lucky to get to the basement on time, you might find an array of weapons, although there are two entrances to the Blast Chamber (for each side of the dorms), and it is very hard to watch both. And the hallways to get down in the dorms are very long, and an extremely large door closes at the 0.5 second mark or so, crushing you if you are in the hall. Then you will respawn, and be killed by the blast. :)

Of course, the Quad Damage is located in my old dorm room, through a false wall. My picture looks down upon you as you get the quad to smite your enemies. I never did finish getting all of the textures right, although I did make one of my fellow classmate's head a texture for portions of the girls' dorm.