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