CHEAT CODES:
On the game menu go to; OPTIONS >KEYBOARD/MOUSE >ALLOW DEVELOPER CONSOLE and change the setting to 'Enable' then press DONE to save new settings. Press the tilde key [ ~ ] on your keyboard to open the console then type "sv_cheats 1" (without quotes) and press ENTER to enable console cheats. You can now type any of the following cheats codes (text in green): changelevel [map name] — Quick change map. give adrenaline — Get adrenaline. give ammo — Refill all ammunition. give autoshotgun — Get auto shotgun. give defibrilator — Get Defibrillator. give electric_guitar — Get Guitar. give first_aid_kit — Get First aid kit. give frying_pan — Get Frying pan. give gascan — Get gas can. give health — Gain health. give hunting_rifle — Get hunting rifle. give machete — Get machete. give melee — Get hunter claws. give molotov — Get Molotov cocktail. give oxygentank — Oxygen tank. give pain_pills — Pain Pills. give pipe_bomb — Pipe bomb. give pistol_magnum — Magnum. give pistol — Double pistol. give propanetank — Propane tank. give pumpshotgun — Pump shotgun. give rifle_ak47 — AK-47. give rifle_desert — Combat rifle. give rifle — M16. give shotgun_chrome — Chrome shotgun. give shotgun_spas — SPAS shotgun. give smg_silenced — Silenced SMG. give smg — SMG. give sniper_military — Sniper rifle. give tonfa — Nightstick. give vomitjar — Boomer Bile. give weapon_grenade_launcher — Grenade launcher. god [0 or 1] — Toggle God mode for entire team. kill — Commit suicide. map atrium — Map Atrium. noclip — Toggle no clipping mode. quit — Quit game. sv_infinite_ammo [0 or 1] — Toggle infinite ammunition. upgrade_add explosive_ammo — Toggle Explosive Ammo upgrade_add incendiary_ammo — Toggle Incendiary Ammo upgrade. upgrade_add laser_sight — Toggle Laser Sight upgrade. z_forcezombiemodel 1 — Spawn zombie model. z_forcezombiemodelname common_male_jimmy — Spawn common male Jimmy Gibbs. z_spawn boomer — Spawn Boomer. z_spawn charger — Spawn Charger z_spawn hunter — Spawn Hunter. z_spawn jockey — Spawn Jockey. z_spawn mob — Spawn zombie mob. z_spawn smoker — Spawn Smoker. z_spawn spitter — Spawn Spitter. z_spawn tank — Spawn Tank. z_spawn witch — Spawn Witch. z_spawn zombie — Spawn normal zombie.

You may need to start the game through the console to use the above cheats. Here's how:
Type the following command below to start a Single Player campaign:
Example: map c1m1_hotel.bsp <Press ENTER> (loads the first map of Single Player campaign).
If you want to set the difficulty level of the game to 'easy' enter the following command (set to 'normal' by default): z_difficulty easy <Press ENTER> (easy, normal, hard, and impossible are your choices).
Alternatively, you can enter the following console command: map c1m1_hotel.bsp; z_difficulty easy <Press ENTER>
You can also change your name at the console by typing: setinfo name Your_Name (e.g. setinfo name John) then press ENTER.
If you want to load and play any maps in the game type the following: maps * <Press ENTER> (gives you the list of all available maps in the game).
Now, you can simply type: map name_of_the_map
Example: map c1m4_atrium.bsp <Press ENTER> (loads the Atrium map).
You can bind a command to a key:
Example: bind p "z_spawn witch" (this will spawn a witch every time you press p).

Here's the list of all available maps: c1m1_hotel.bsp c1m2_streets.bsp c1m3_mall.bsp c1m4_atrium.bsp c2m1_highway.bsp c2m2_fairgrounds.bsp c2m3_coaster.bsp c2m4_barns.bsp c2m5_concert.bsp c3m1_plankcountry.bsp c3m2_swamp.bsp c3m3_shantytown.bsp c3m4_plantation.bsp c4m1_milltown_a.bsp c4m2_sugarmill_a.bsp c4m3_sugarmill_b.bsp c4m4_milltown_b.bsp c4m5_milltown_escape.bsp c5m1_waterfront.bsp c5m1_waterfront_sndscape.bsp c5m2_park.bsp c5m3_cemetery.bsp c5m4_quarter.bsp c5m5_bridge.bsp credits.bsp tutorial_standards.bsp tutorial_standards_vs.bsp