You use the Half-life console to play new levels downloaded from "internet" or old levels you allredy has,
and ofcourse, cheat cheat cheat!!! You don't have to download any files or something, you just do like me...

1. At first you have to do a shortcut of hl.exe (the original half-life file). Place it at your desktop.
2. Now, rename it to "Half-life console" or something like that...
3. Right click at the icon "Half-life console" and choose "properties".
4. In the name field it would be something like "C:\sierra\Half-Life\hl.exe".
Just left a space after "hl.exe" and write, "-dev -console".
5. Your console is now ready. Press ok and start the shortcut you have
made.
6. When you've start half-life and you're in the main menu press the gray button
in the left corner.
7. Now, when you're into the console, "type sv_cheats 1" and press enter.
8. Restart the console and press the button "console". Write "sv_cheats"
9.There are many different cheats you can use... read the description below.

The half-life cheat codes.

/GOD = God mode
/notarget = The enemy's can't see you.
/Impulse 101 = All weapons (start working after an autosave).

To play a level in half-life type "/map xxxx". For example
"/map c0a0". Below it's a full list of all sections in Half-life!!

To get an specific weapon type "give", for example "give weapon_shotgun".
To get ammmo type for example "give ammo_mp5clip"
And ofcourse, to get items type for example "give item_healthkit"

Here is the full list of all item's, ammo's and weapon's.

Item's
item_airtank
item_antidote
item_battery
item_healthkit
item_longjump
item_security
item_sodacan
item_suit

Ammo's
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

Weapon's
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_rpg
weapon_satchel
weapon_shotgun
weapon_snark
weapon_tripmine

Map Names
Single Player:
c0a0 c0a0a c0a0b c0a0c c0a0d c0a0e
c1a0 c1a0a c1a0b c1a0c c1a0d c1a0e
c1a1 c1a1a c1a1b c1a1c c1a1d c1a1f
c1a2 c1a2a c1a2b c1a2c c1a2d
c1a3 c1a3a c1a3b c1a3c c1a3d
c1a4 c1a4b c1a4d c1a4e c1a4f c1a4g c1a4i c1a4j c1a4k
c2a1 c2a1a c2a1b
c2a2 c2a2a c2a2b1 c2a2b2 c2a2c c2a2d c2a2e c2a2f c2a2g c2a2h
c2a3 c2a3a c2a3b c2a3c c2a3d c2a3e
c2a4 c2a4a c2a4b c2a4c c2a4d c2a4e c2a4f c2a4g
c2a5 c2a5a c2a5b c2a5c c2a5d c2a5e c2a5f c2a5g c2a5w c2a5x
c3a1 c3a1a c3a1b
c3a2 c3a2a c3a2b c3a2c c3a2d c3a2e c3a2f
c4a1 c4a1a c4a1b c4a1c c4a1d c4a1e c4a1f
c4a2 c4a2a c4a2b
c4a3
c5a1

If you want to come to the beginning of
a level skip the last letter if there are
over 5 letters in the map name