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 lots of 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 
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 
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.