Left 4 Dead
If you're playing the original L4D levels in Left 4 Dead 2, you will need to follow the method shown in the Left 4 Dead 2 page. To disable the hud in the original Left 4 Dead, use this method:
Find and edit your autoexec.cfg with a text editor (like Notepad or Wordpad).
Add the following commands:
bind "f1" "sv_cheats 1"
bind "f2" "sv_cheats 0"
bind "f3" "r_drawvgui 0 ; crosshair 0 ; cl_glow_blur_scale 0"
bind "f4" "r_drawvgui 1 ; crosshair 1 ; cl_glow_blur_scale 1"
When in game, press F3 to disable the hud, F4 to enable hud
NOTE: this method of disabling the hud also removes the menus, so use F4 to turn them back on when needed.
other flawed console commands:
cl_drawhud 0 - only disables part of the hud
hidehud 4 - removes the hud, but also disables weapon switching.
crosshair 0 - Removes crosshair
cl_glow_blue_scale 0 - Removes glowing around npc's, players, and items.
r_drawviewmodel 0 - disables weapon (good for screenshots)
r_drawviewmodel 1 - enable weapon
If you have random beeping or static sounds in game, rename this directory:
type this in console:
That method may prevent some sound effects from looping properly, like rain or fire.
To fix crashes: Disable Multicore Rendering in the advanced video options.