So I’ve been playing Borderlands 2 and designing “Run & Gun” mechanics.

I did some research on firearm mechanics like a year and a half ago (Dec. 2012?) that was fascinating and served a role in the development of some homebrew powers, particularly ranged/area attacks and burst/blast attacks.

Taking cues from the kinds of gun mods/stats available in Borderlands — from when I originally did the research — I looked at the physics related to firearms, and what sorts of factors were at play with projectile… physics-y… stuff.

Seriously, there are so many terms to keep track of that I get lost myself when discussing mass and velocity, air resistance, deceleration, force, recoil, climb, stability, and it’s all just… Argh. Not my field. Fascinating but not my field.

My research did help with my perspective of physics as a whole. It filled in a gap I was missing as compared to say, bio-mechanical force weapons like swords, axes, and spears. Martial arts started making a lot more sense.

Blah, blah. I’m getting off-track.

I realized at a certain point that only so many mechanical properties — from a game design perspective — could be based on a weapon’s type, and that includes accuracy, damage, energy type, reload speed, and so on, and so forth.

I came up with a short list of energy types associated with weapons:
Bullets deal thunder damage.
Laser beams deal radiant damage.
Plasma bolts deal fire damage.

Now, special cartridges might exist to deal oddball energy types like acid or poison or whatever — Mass Effect makes a compelling argument for “poison” radioactive rounds — if radiation caused “poison.” (It actually has a variety of effects.)

Maybe ammunition should be an item, separate from firearms. That’s cool.

Because unlike the magic guns of Borderlands, it really doesn’t make sense for a firearm to transform discharged ammunition into corrosive or incendiary projectiles. Those ought to be properties of the ammunition itself.

Have you ever wished for a straightforward armor-piercing round in Borderlands? You better believe I have. *grumbles* Stupid magic corrosive weapons.

The problems that arise however, include how much of an impact the character’s abilities actually have on the weapon’s performance — you arrive at a point where everything is being determined by the firearm, and that’s almost boring.

What I figured was this — a character’s Dexterity (“point and shoot”) helps determine damage. So the basic formula is [W] + Dexterity modifier.

Accuracy is determined almost entirely by weapon traits [barrel + quality].

Now, for the sake of small-map tactics a la 4e grids — virtually all firearm attacks must have the same range — between 5 and 10 squares.

To complement that, if you’re using pistol rounds within 5 squares you get a damage bonus — and if you use rifle rounds against a target 6+ squares away, you get a similar damage bonus. Maybe not super realistic — but realism is hard.

I was at a loss for how to represent burst- versus automatic fire.

It occurred to me that the basic idea behind each is to try and deliver multiple bullets to the same location — which barring the accuracy of say, the initial discharge, would probably tend to represent a fairly flat damage bonus.

So burst-fire would probably be an easy +2/3/4 per-tier damage bonus.

There’s more to work out here, but this is the basic idea so far.