All codes from HALF-LIFE 2 are suitable.

Start the game with a command line parameter: your game directory \ INFRA \ infra.exe -dev -console.

Here is how you add a command line parameter to a video game's shortcut icon on your PC desktop:

Locate the shortcut to the video game on your desktop.
Right click the file and select Properties.
Under the shortcut tab, you will see an area that says Target, this will list the exact location of the file within quotation marks.
Modify the Target adding the command line variables after the last quotation mark.
Press apply and start your game via the shortcut.

During the game access the console by pressing the tilde (~), type sv_cheats 1, then enter the following codes:

god - immortality
give - the item of weapons
buddha - reduce health
hurtme # - hurt the player (# - value of damage)
impulse 101 - all weapons
notarget - invisibility
noclip - walk through walls
maps -  list of maps
map - download a map
+mlook - mouse lock
viewmodel_fov # - set the size of the weapon (54 by default)
exec - run the script
cl_showfps 1 - number of frames per second
npc_create - create NPC
setpos - move the player
sv_gravity # - set gravity value
sv_stopspeed # - set minimum stop speed
sv_maxvelocity # - the maximum speed of the moving object
air_density # - set the air density
sv_soundemitter_filecheck - message switch for the lost * .wav files
mat_numtextureunits # - the restriction of number of textures