Left 4 Dead 2

Left 4 Dead 2

Enter the Steam control panel then select the "My games" tab.
Right Click the "Left 4 Dead 2 Demo" option then select "Properties".
Select "Set Launch options" then enter -console and accept it.

OR run the game with "-console" parameter if you have non
steam version of the game

Start the game, and the console window should now appear.
Enter "bind p toggleconsole" as a console command.
Click and close the console window and start a single player game.

(you can alos activate the console in the menu options -> control options
in this case you need to press [~] tilde to open it)

Press [P] during gameplay to display the console window (or [~], tilde button),
then enter "sv_cheats 1" to enable cheat mode.

If the message:
"Can't use cheats now; please exit to main menu and start your own listen
server with "map mapname" so that you could enable cheats."
appears,

enable the map c5m1_waterfront or map c5m2_park code. You will return to
the main menu. Enable either map code again, then enable the sv_cheats 1
code again. You can now enter one of the following cheat codes:

god [0 or 1]                     - Toggle God mode for entire team
give health                      - Gain health
give defibrilator                - Defibrillator
give adrenaline                  - Adrenaline
give first_aid_kit               - First aid kit
give pain_pills                  - Pain Pills
kill                             - Commit suicide
quit                             - Quit game
noclip                           - Toggle no clipping mode
upgrade_add incendiary_ammo      - Toggle Incendiary Ammo upgrade
upgrade_add explosive_ammo       - Toggle Explosive Ammo upgrade
upgrade_add laser_sight          - Toggle Laser Sight upgrade
give weapon_grenade_launcher     - Grenade launcher
give melee                       - Hunter claws
give rifle_desert         - Combat rifle
give rifle_ak47         - AK-47
give sniper_military         - Sniper rifle
give pistol_magnum         - Magnum
give smg_silenced         - Silenced SMG
give shotgun_chrome         - Chrome shotgun
give shotgun_spas         - SPAS shotgun
give tonfa                 - Nightstick
give vomitjar                 - Boomer Bile
give electric_guitar         - Guitar
give frying_pan         - Frying pan
give machete                 - Machete
give pistol                 - Double pistol
give pumpshotgun         - Pump shotgun
give autoshotgun         - Auto shotgun
give smg                 - SMG
give rifle                 - M16
give hunting_rifle         - Sniper rifle
give molotov                 - Molotov cocktail
give pipe_bomb                 - Pipe bomb
give propanetank         - Propane tank
give gascan                 - Gas can
give oxygentank         - Oxygen tank
give ammo                 - Refill ammunition
sv_infinite_ammo [0 or 1]        - Toggle unlimited ammunition
z_spawn spitter         - Spawn Spitter
z_spawn jockey                 - Spawn Jockey
z_spawn charger         - Spawn Charger
z_spawn zombie                 - Spawn common zombie
z_spawn mob                 - Spawn zombie mob
z_spawn boomer                 - Spawn Boomer
z_spawn hunter                 - Spawn Hunter
z_spawn witch                 - Spawn Witch
z_spawn smoker                 - Spawn Smoker
z_spawn tank                     - Spawn Tank