Half Life Codes - Overall Rating 9 out of 10 - Cheats - http://maxpages.com/rjtgames/Half

Command line parameters
To enter these codes you must edit the Half-Life icon on your START menu.
Right-click on the START icon on the Windows task bar.
Click on OPEN.
Find the Half-Life icon and right-click on it.
Click on PROPERTIES.
Add the desired parameter to the end of the field that says TARGET or CMD_LINE. For example, to enable developer's mode you would change the line to read: "C:\Sierra\Half-Life\hl.exe -dev"
Without further ado, we bring you the codes:

-console
Enables the console. To access it, press tilde (~) while playing. See "Console Codes" for information on using the console.

-dev
Developer's mode. Enables the console and displays debugging information while playing. Useful if you're having technical difficulties and want to find out why.

-heapsize x
Tells Half-Life how much RAM (memory) it can use. For example, if you want it to use 32Mb of RAM then enter the parameter "-heapsize 32768". CAUTION! Do not request more memory than your computer has.

-nointro
Skip the introduction movies.

-noip
Removes the D.U.N. box for playing on LAN's (local area networks.) Remove this command whenever playing on the internet. If you don't you won't be able to play on-line.

-noipx
Use this if you receive an IPX error when playing on a LAN.

-numericping
Replace's the Half-Life server browser's "green dot" latecy info with real numbers. Only available in v1.0.0.8 or later.

-startwindowed
Start Half-Life in window instead of fullscreen.

-wavonly
Disables Direct Sound and plays SFX in wav files. Try this if your sound card stutters or you don't have DirectSound drivers.

Console Codes

Load the game using the “-DEV –TOCONSOLE” command line parameters. Your command line should look like this:
HL.EXE –DEV –TOCONSOLE

(If the text does not disappear, then press the tilde key [ press the tilde key [] and type “sv_cheats” at the console window to activate cheat mode. (The underscore “_” denotes a space.)You must either die or reload your game before you this code takes effect
(Note: To use cheats on a saved game, enable Cheat mode and load the saved game.)
submitted by Mr. Evil, Cyberavk, GubGubby, Jeff S and many others

Adjust gravity
Enable Cheat mode. Then press +(tilde)+and+enter+“sv_gravity+<1–800>”+at+the+console+window.+(The+underscore+“_”+denotes+a+space.)

(Note:+The+default+is+“sv+gravity+800”.)
submitted+by+Robert+Bava

All+weapons+and+ammo
Enable+Cheat+mode.+Then+press+ (tilde) and enter “/impulse 101” at the console window.

Create item
Enable Cheat mode. Then press where item is the object you wish to create. Example:

Give item_airtank

Object list

Ammunition
Ammo_357
Ammo_9mmAR
Ammo_9mmbox
Ammo_9mmclip
Ammo_Argrenades
Ammo_Buckshot
Ammo_Crossbow
Ammo_Egonclip
Ammo_Gaussclip
Ammo_Glockclip
Ammo_MP5clip
Ammo_MP5grenades
Ammo_RPGclip

Items
Item_airtank
Item_antidote
Item_battery
Item_healthkit
Item_longjump
Item_security
Item_sodacan
Item_suit

Weapons
Weapon_357
Weapon_9mmAR
Weapon_9mmHandgun
Weapon_Crossbow
Weapon_Crowbar
Weapon_Egon
Weapon_Gauss
Weapon_Glock
Weapon_Handgrenade
Weapon_Hornetgun
Weapon_MP5
Weapon_Python
Weapon_QuantumDestabilizer
Weapon_RPG
Weapon_Satchel
Weapon_Shark
Weapon_Shotgun
Weapon_Tripmine

Disable clipping and flight modes
Enable Cheat mode. Then press (tilde) and enter “/noclip” at the console window.

God mode
Enable Cheat mode. Then press +(tilde)+and+enter+“/god”+at+the+console+window.+

Opponents+ignore+you
Enable+Cheat+mode.+Then+press+ (tilde) and enter “/notarget” at the console window.
submitted by Neo

Quick Weapon Reload
First of all, this only works for weapons with slow reload times, like the magnum and the tranquilizer crossbow. Upon running out of ammo in your clip, you will begin to reolad your weapon. If you want to fire faster, simply changes your weapon while in the reloading animation, and then switch back to the weapon you want to use, and realoading will be complete.
NOTE: This trick does not work with Half-Life 1.0.1.0 or higher.
submitted by Brian W and Sammy Dalati

Select level
Enable Cheat mode. Then press where name is one of the map names below.

Maps

Single-player maps:
Generally, single player maps have the following form:
c<1-5>a<1-5>letter

A few valid map 1P map names are, “c1a2b”, “c5a1” and “c2a5x”.

Multi-player (Deathmatch) Maps:
Boot camp
Bounce
Datacore
Lambda bunker
Shark pit
Stalkyard
Subtransit
Undertow

Hazard courses:
t0a0
t0a0a
t0a0b
t0a0b1
t0a0b2
t0a0c
t0a0d

Sniper Mode with any weapon
If you have a crossbow, you can get sniper mode on any weapon, and here's how: Simply quick-save your game, go to the crossbow and zoom in, and then quick-load. When the game pops up again, you will be zoomed in on the weapon you had when you saved, and can cycle through the others as normal. To zoom out, just go back to the crossbow and press 2nd attack.
OR

Enable the console by typing "-dev" or "-console" (without qoutes) as mentioned in one of the above codes.

Start up the game, and enter a new game, or load a saved one. Now hit the key to bring up the console. Type the following, where * is the key of your choice. (Keep in mind, you must bind all three commands to different keys.

bind * "fov 20"

bind * "fov 50"

bind * "fov 90"

The first will bring you in to a very close zoom. Second is mid-range, and third is the command to bring you back to the normal view. It works with any weapon, though it will not change the mode of fire or increase/decrease accuracy.
submitted by Armach , Zach C. and Da man in da South

Third person perspective
Enable Cheat mode. Then press ~ (tilde) and enter “/thirdperson” at the console window.