Each team meets in the middle, and see who gets killed first. If you plan to survive, the only thing you want to be is an hwguy, a soldier, or a demoman. Brute force is the key, which is pretty much what you get with a hwguy, soldier, or demoman. If you have a good video card, you can play this map. The massive amounts of spam will slow your computer to 5 fps in very little time.
Nothing is more humorous than a fat guy running around with a crowbar.
As much fun as this deathmatch map is, there is one big problem. There is no respawn security. If an enemy waits outside your door, they can easily sneak in because when one door opens, they both open. This allows the enemy to completely mow down anyone hiding in the respawn, then mow them down again when they come back to life. Two or three enemy hwguys can completely occupy your respawn for a very long time.