I don't think we ever really handled sizes correctly in BESM ... until now.
In BESM 1, I wrote the Size Change attribute. It allowed characters to grow or shrink, but didn't provide for anything else such as extra damage or lifting capacity, etc. This worked fine for BESM 1s rules-light approach, since the players and GM could fill in the gaps and handle secondary effects from changing sizes with simple game logic.
In BESM 2, Size Change was expanded to include other effects as well. For example, Level 5 represented a 1000% increase in height, and added +10 damage to muscle-powered attacks. Unfortunately, this caused several problems. First, the damage increase was not in proportion to the size increase. Then, the cost of the Size Change Attribute wasn't balanced with the cost of the Focused Damage Attribute (which could also add damage to attacks). And I won't even go into the problems associated with the muscle-powered special attack ability, which we applied unevenly. Finally, all the other things associated with size change was not accounted for.
In Big Ears, Small Mouse (BESM 2 supplement), we presented an alternate system for dealing with really small creatures. Small characters inflicted "Scratch Points" instead of "Health Points" -- roughly on a 1/5 ratio. This worked fairly well when two mouse-sized characters were fighting each other (they just deliver normal damage in Scratch Points, rather than reduced damage in Health Points because they were small), but didn't integrate well with normal-sized or larger-sized characters.
In BESM 3, I wanted to get it right. I wanted a template system that was easy, logical, and internally consistent. I turned to the different size templates in D&D for a peak at how they handled things. While it wasn't perfect, it gave me the basis of the Size Templates in BESM 3.
Now BESM 3 has 17 size categories, ranging from Speck (1-4 mm; bug-sized) to Monumental (500 m; mega-kaiju-sized). Each size rank that differs from Medium (ie. human) change the following:
* lifting capacity
* damage delivered when hitting others
* damage received when being hit by others
* hitting with a ranged attack
* being hit with a ranged attack
* thrown weapon distance
* running speed
It might sound a little complex, but it's not. For most games where everyone is playing a medium-sized human, there's no need to worry about size. In a mixed-size game, though, the size ranks make a lot of sense. Consider the following classic fantasy combat situation: a hobbit (Small) fighting an giant (Huge).
The hobbit inflicts -4 damage when striking the giant, since he's not as strong. He also suffers an extra 4 damage from attacks. Being small, the hobbit gains a +1 to defend against all ranged attacks (it's hard for thrown rocks to pin-point him) and a +1 to hit other the giant with a sling (since the giant makes a big target).
It's the reverse for the giant. He gains +8 damage when striking the hobbit, because he's big, and has 8 Armour. He suffers a -2 penalty to attack and defend against all ranged weapons due to his size -- smaller opponents are hard to see and the giant is the proverbial "broad side of a barn" because he's so big.
The net change for the combat is: hobbit's damage is reduced by 12 when hitting giant (-4 damage + 8 Armour), while giant's is increased by 12 when hitting hobbit. Hobbit has a +3 advantage in ranged attacks (both defending and attacking) against the giant.
What really works with these categories, though, is the independence of the modifiers on the opponents. When I say the giant "giant +8 damage when striking the hobbit," I'm really saying "gains +8 damage when striking any opponent." If the giant is attacking a red dragon (Monstrous), he still gains +8 damage ... but that isn't enough to overcome the dragons 24 Armour due to size.
What if the entire game uses non-Medium characters? Say, a pixie game where everyone is 9 cm tall (Fine).That seems like a lot of modifiers to use in every single combat situation! This is where the brilliance of the system really shines. A Fine-sized pixie reduces attack damage by 16 ... but also receives an extra 16 damage when attacked. The next effect cancels out when a pixie attacks another pixie: subtract 16 damage, but then add 16 damage. So a pixie-pixie fight is handled without modifiers the exact same way as a human-human or giant-giant or dragon-dragon battle. The modifiers are only relevant when different sizes are battling.
As you can tell, I'm pleased as punch how size now works in BESM 3: easy, logical, and consistent. And best of all, if you don't want to deal with those modifiers, just discard all size rules and you have the system from BESM 1.
I deserve a cookie.