http://pc.ign.com/articles/959/959549p1.html
Survival mode sounds intense.
Heres just a piece of the article:
Unattributed Quote:
How furious is it? Consider this: In all of the play testing that the Valve designers have done while creating this mode, none of them have ever survived past the 10 minute mark. We're told the company best so far was about nine minutes, with a team of elite players battling like crazy to keep one another alive. Our experience at Valve averaged around three or four minutes a round, but they're like the fastest three or four minutes of your life.
What makes it so challenging is that the Survival mode doesn't waste time building up. After the initial wave of zombies you'll start getting hit by waves of special zombies; these are the hunters, smokers, boomers, and tanks. You'll get multiples of them at a time; I often saw two or three hunters or smokers leaping around the battle while the mindless horde minions were everywhere. In one battle, we had the tank, a boomer, a couple of smokers, and a hunter hitting us at the same time. We're told it's even possible to get two tanks at the same time, a prospect that seems both ludicrously unfair and hilarious at the same time.
The way to survive as long as possible is to work together, which means sticking together as well as doing everything you can to protect the weakest member of the group, especially if they're knocked down and must be revived. There's plenty of equipment available in various areas of the level; some of these areas only open up during the match, so after you exhaust all the equipment in one room, you'd best move as a group to the next. One of the most dangerous moments is when you run out of ammo; you then have to make a coordinated move to one of the few ammo points on the map to restock.
So what's in it for you? Well, beside the intense action, there are all sorts of personal records you can accumulate. The most obvious one is trying to get a best time for each of the 16 Survival levels in the game. There are extra incentives as well. You can earn bronze, silver, and gold medals if you survive long enough. Though the medal times for each map will be tailored for each map, right now the basic idea is that you need to survive for at least four minutes to get bronze, six minutes to get silver, and eight minutes to get gold. (In our play session, the best we ever got was within a minute of earning silver.) Of course, online leaderboards will also let you compare your times with those of our friends for bragging rights.