How to play:

Use WASD to move.
    Move the mouse to look around.
    Press the left mouse button to fire.
    To reload, press R.
    
    Yellow powerups restore clips.
    Red powerups restore health.
    
    Beating a level means the game gets harder,
    but you get more points for each zombie.

FAQ:

    Q: Why can I still shoot after running out
       of ammo?
    A: That's supposed to simulate the pistols
       in the original game. When clicking like
       that, you only fire at half the normal
       speed.
    
    Q: Where's the exit?
    A: On the first level, go to the far left
       wall, then follow that wall to the far
       north. Then go east and the exit should
       be somewhere just south of you.
       You're looking for a red room.
    
    Q: Where are the powerups? Why are there
       so many zombies just at the start?
    A: That's random! The levels are always
       the same, but the location of zombies
       and powerups change each time you play.
    
    Q: Didn't you just call this "Left 4k Dead"
       to get some free publicity?
    A: Kinda. :D It's a game about zombies,
       with some elements taken from the 
       AWESOME game Left 4 Dead, and the name
       is pretty darn punny if you ask me.
    
    Q: Why don't you sell this?
    A: Because I have an awesome day job making
       games at king.com.

About the game:

    Left 4k Dead was made by Markus Persson,
    for the 2009 Java 4k Competition.
    The entire game is less than 4kb.
    

    The game is inspired by Left 4 Dead by
    Valve Software.
    
    
    
    Source code

Interwebs:

    On the day before xmas, Left 4k Dead
    suddenly hit the tubes. I'm very happy
    for all the nice feedback I have received,
    and I'm definitely planning on letting it
    go to my head. :-D
    
    Thank you!
    
    Major ego boosting mentions include:
    Kotaku (Yay!)
    Reddit
    Shacknews
    Digg