*SECOND. ARMOR MODULE.* news - Argentum mod for Half-Life 2

1) There are 8 armor classes: unarmored, light armor, medium armor, heavy armor, vehicle armor, heroic armor, HEV armor and Divine armor.
2) Armor subtracts damage taken by some value and then reduces some part of it. The value of damage subtraction is constant to NPC, the part of damage then reduced differs for damage types, with the exception of bullet damage - each gun has its own light-medium-heavy-etc armor penetration factor.
For instance, shotgun fires 9 pellets each of which deals 20-25 damage (the only gun that does random damage currently), giving the average of 200 damage if all pellets connect. Also it has medium-armor-penetration factor of 30 percents. Combine soldier has 6 armor quantity value and a medium armor.
So, if we take 22 for average pellet damage, we subtract 6 damage and take a total of 16 damage, then we multiply it by 0.3 and then by 9 because of all pellets and we got 43 damage done if all pellets connect to the target. If the shot is done point-blank and at a right angle (see BALLISTICS MODULE for more info) Well, shotgun has the poorest armor penetration in game to compensate for its huge base damage. Aim for the head if you engage armored opponent.
3) HEV armor is actually split into 2 parts: the "basic" suit protection and suit charge. Basic protection uses weapon's factors of penetrating light, medium and heavy armor to calculate multiplier. The charge absors damage depending on its (charge) value: 80% if charge is higher than 150, 75% if charge is higher than 100, 66% if charge is higher than 50, otherwise 50%.
4) Some metrocops and non-medic rebels have light armor, combine soldiers, late metrocops and antlion guard have medium armor, combine elites, metrocop elites and hunters have heavy armor. G-Man has Divine armor. Player gets HEV Armor when he gets hev suit. All mechanical units from manhacks to striders have vehicle-type armor which is very difficult to damage through, if you're using non-explosive and non-electrical damage.