Press [F1] to display the console window, type one of the following codes, press [Enter], then press [F1]

Result Code

God mode - cht_bGod
All weapons - cht_bGiveAll
Full health - cht_bRefresh
No clipping - cht_bGhost
Invisibility - cht_bInvisible
Flight mode - cht_bFly

[DemoVersion]

At the Main Demo Screen (where you can select Single Player, Demo, etc.) Hit the Tilde Key to bring up the console. Type in one of the following:

To see a list of variables that can be changed, type in the following:

ListSymbols()

To change the damage done by enemies, do the following:

gam_afDamageStrength[level]=(Damage value)

level:

0 = Easy
1 = Normal
2 = Hard
3 = Serious

Damage Value:

0.0 = no damage
1.0 = normal damage
2.0 = 2 times damage

Example:

gam_afDamageStrength[0]=0

Makes it so that in the Easy level, no damage is done to you.

To increase the amount of ammo, type in the following:

gam_afAmmoQuantity[Level]=[Ammo Quantity]

Where

level:

0 = Easy
1 = Normal
2 = Hard
3 = Serious

Ammo Value:

0.0 = no ammo
1.0 = normal ammo
2.0 = 2 times ammo

Example:

gam_afAmmoQuantity[0]=2.0
Puts lotsa ammo out there...

To change the enemy movement speed, type in the following:

gam_afEnemyMovementSpeed[level] = Speed

Where

level:

0 = Easy
1 = Normal
2 = Hard
3 = Serious

Enemy Speed Value:

0.0 = They don't move (really funny)
1.0 = Normal Speed
2.0 = Way Fast

Example:

gam_afEnemyMovementSpeed[0]=3.0

Makes the enemy run to you really fast on the easy level.

gam_afEnemyAttackSpeed[level] = Speed

Where

level:

0 = Easy
1 = Normal
2 = Hard
3 = Serious

Damage Value:

0.0 = They don't move (really funny)
1.0 = Normal Speed
2.0 = Way Fast

Example:

gam_afEnemyAttackSpeed[0]=2.0

Makes it so that on the easy level, enemies attack you really fast