Demo

The Left 4 Dead demo was initially released on 6 November, 2008. It contains the first two chapters of the No Mercy campaign, playable in the Survivors' co-op mode, both locally and online.

The demo will be released to the public on 11 November, 2008. It is confirmed that the demo will come out for Xbox360 as well as for PC.

Joining the Infected Team in the DEMO
Otherwise known as "Versus Mode"

-Quick run-through of the demo 

The demo has a 2 maps, and the ability to play Those 2 maps either single player, or co-op. But the ability to play those 2 maps in the "Versus" game mode, has been blocked in the demo...Right?

Wrong

The versus mode allows a total of eight players in the actual release, and allows 4 players to play on the Infected team(as the boss zombies) and attempt to wipe out the survivors team (Contrary to the campaign mode where you can only play as survivors on a team of 4 MAX). The game mode is a little bit buggy, but can be stable if done right.

Right now you're probably asking, How do I take on such a wonderful task of annihilating the survivors? Simple, first enable your developers console by going to Options<Advanced<Enable developers console and then press the Tilde key (` ~) under your escape key, and type in sv_cheats 1.

(Remember, this HAS to be Either Your server, or one that has sv_cheats set to 1 to do this!)

then type the following in your console as well:

ent_fire !self setteam 3 (^-This sets you to the infected side-^) (^-Once you type this in, the game will restart with you on the infected team-^) director_force_versus_start 1 (^-This sets the survivors to start without you - Use only if there are no other players on the survivor team!-^) z_spawn tank

or

z_spawn hunter

or

z_spawn boomer

or

z_spawn smoker (^-these are the things you can spawn as, type one in while dead to spawn as one-^)