Saturday, February 18, 2012

Alternative Damage System

After reading over Jason's post I've been giving it some thought about the system he proposes there and how to keep it simple as clearly so much die matching can become a real pain.  Previously I've played with AC (armor class) systems that require a die roll to hit (D&D's THACO), or on the other hand some AR (armor rating) the damage roll needs to exceed to overcome the armor and inflict damage.  Jason's proposal seems a lot more granular albeit a bit more complex to handle.  In the next few posts I'll be going over this model with some statistical data to see how well the game balances out.

The objective is to create a balanced combat system that can support medieval weapons, modern age weapons, magic and future weapons as well as mecha and fantastic creatures.  Now lets get started on what I've got so far.

Overall the idea is that you have weapon and armor die ratings.  For example:

Weapons have the classic ndm*p + q description.  Where n is the number of die to roll, m the die type, p the multiplier and q the bonus (magical weapons for example in D&D).

dagger 1d4
sword 1d8
arrow 1d6
bastard sword 2d8
magic missile 1d6
lightning bolt 3d6
fireball 3d6
.22 pistol 2d6
.223 M16 round 2d8
napalm 6d4
white phosphorus 4d4
flame thrower 5d6
hand granade 3d6
sniper round 2d10
50 cal 2d12
20mm cannon 1d10*10
HEAT round 2d10*10
AP round 2d10*10+2

leather armor 2d4
chain mail 3d6
plate mail 3d8
balistic vest 2d8
balistic vest+ceramic 2d10
blast vest 5d8
APC armor 50mm 2d10*10
Tank armor 100mm 3d10*10
Chobham armor 5d10*10+3

As you can see from the last entries on the table armor also has a die roll.  What is defined is the number of die rolls it has available to match the damage rolls on an individual level.  For example a dagger can roll between 1 and 4.  The leather armor can roll two values between 1 and 4, not one single value between 2 and 8 as is common in 2d4 rolls (as explained in Jason's blog).  Example

Dagger rolls : 2
Leather rolls: 1, 3

We order from highest to lowest:

Dagger : 2
Leather : 3, 1

The leather effectively stops the dagger.  It has in a way two opportunities to stop it.  This concept of opportunities or statistically speaking of another event occurring given a prior event is what makes this mechanism interesting.  The leather armor still has a good chance of rolling a high value after it rolled a low value on the first roll.  Now lets match the leather against the sword.

The sword rolls 1d8.  The leather has two opportunities to stop it, but it can only roll up to a 4.  For example:

Sword rolls : 3
Leather rolls: 2, 3

The leather once again stops the blow.  Since after we order the values the leather's 3 stops the sword's 3.  But the sword could very well have rolled 5, 6, 7, or 8.  Values the leather can never stop.  For example:

Sword rolls : 6
Leather rolls: 4, 4

Even when the leather rolls two 4's (the best it can) it can not stop the sword.  The sword still defeats the armor because it is simply a better weapon.  Actually 50% of the swords rolls (5,6,7, and 8) defeat the armor.  You want better protection get chain mail (3d6) that's three opportunities at stopping the sword, but the sword can still defeat you cleanly 25% of the time (rolls 7, or 8).  Want better than that get plate mail which is the first that can totally stop a sword dead on its track.

Now after having the computer run some number crunching on 100000 combat cycles per weapon armor pair we have the following table with odds of perforating the armor and causing damage:

leather chain mail plate mail ballistic vest vest+ceramic

dagger 1d4 22.00% 4.00% 2.00% 5.00%
sword 1d8 61.00% 38.00% 19.00% 27.00%
arrow 1d6 48.00% 17.00% 7.00% 8.00%
bastard sword 2d8 87.00% 65.00% 41.00% 58.00%
magic missile 1d6 48.00% 17.00% 7.00% 8.00%
lightning bolt 3d6 100.00% 62.00% 45.00% 100.00%
fireball 3d6 100.00% 62.00% 45.00% 100.00%
.22 pistol 2d6 78.00% 38.00% 21.00% 25.00% 19.00%
.223 M16 round 2d8 88.00% 65.00% 41.00% 42.00% 32.00%
napalm 6d4 100.00% 100.00% 100.00% 100.00% 100.00%
white phosphorus 4d4 100.00% 100.00% 100.00% 100.00% 100.00%
flame thrower 5d6 100.00% 100.00% 100.00% 100.00% 100.00%
hand granade 3d6 100.00% 62.00% 45.00% 100.00% 100.00%
sniper round 2d10 92.00% 78.00% 62.00% 61.00% 47.00%
50 cal 2d12 95.00% 85.00% 74.00% 73.00% 62.00%
20mm cannon 1d10*10 100.00% 100.00% 100.00% 100.00% 100.00%
HEAT round 2d10*10 100.00% 100.00% 100.00% 100.00% 100.00%
AP round 2d10*10+2 100.00% 100.00% 100.00% 100.00% 100.00%

This table shows the odds of the given weapon penetrating the given armor.  For example the dagger has a 22% chance of causing damage to a character wearing leather armor.  Chain mail and plate mail go down to 4 and 2 % respectively.  A bastard sword has a high probability of causing damage to leather (87%) vs plate mail (41%)

What I find interesting is that ancient armor also has a good chance of stopping modern weapons.  A .22 cal can penetrate plate mail 21% of the time.  Which sounds reasonable to me.  Some of you will notice it has a better chance of penetrating a ballistic vest even when it is more modern.  And that is a good point, but plate mail is bulkier and covers a great deal more of ones body than a vest which is lighter and covers only the chest area.

This difference is seen in the number of die or overall coverage the armor provides, 3d8 for plate mail and 2d8 for the vest.  Each die represent more cover capacity by the armor while the value of the die itself represents penetrating power.  Napalm, flame throwers and general area of effect weapons always achieve some degree of damage and are marked as 100%.  For example plate mail against a flame thrower ( or dragon !) has a good chance of stopping 3 of its rolls, but 2 will certainly go through uncontested.  Example:

Dragon breath (aka medieval flame thrower) roll : 5 4 3 3 1
Armor Plate Mail roll : 7 6 5

The dragon breath's 5, 4, and 3 rolls are stopped by the armors 7, 6 and 5 rolls, but being engulfed in flames the character still takes 3 + 1 = 4 points of damage from the lower die rolls.  This is sheer heat the armor can't stop as it isn't air tight.

Beyond that we have the BFG rounds which have a multiplier and just beat the **** out of everything else, but enough for today.  I'll do some more math on this and see how it works out.  We still need to cover bonuses like the +1, +2, etc.  Which significantly change the balance of play as you'll see in a later post.  Making technology and magic so much more fun.  A 2d4+1 leather armor in this mechanism isn't as crappy as you'd believe if you come from D&D based systems.  I'll keep you posted!
Post a Comment