Hilariously, despite the fact that most RPGs dedicate the majority of their system section to combat it is one of the things RPGs have a very hard time representing. Now, this isn't the rules systems' fault. Combat is a very fluid thing between people, and to try and break it down into mechanics is a daunting task, one that begs the question of do you go for stream lined rules or essentially require a master's degree in your game to use the system right. Every system does it in its own way. For this post I want to talk about some of the challenges. Also, for the record, I'm going to be focusing on melee combat in a duel scenario more than mass combat.
Defense Is Where It Falls Apart
I'm going to cut to the chase. In most systems defense is where the system falls apart in failing to represent actual combat, at least first. The reason for this is simple: the more die rolls you have the more you slow the game down. In effect, every die rolls brings people out of the game and into the OOC area around the game. Old World of Darkness had you roll both sides. Shadowrun has you roll both sides. And combat in both those games slows down dramatically. In other games, designed to be more combat heavy (Shadowrun and Vampire despite being brutal in combat try to encourage other forms of dispute resolution) your ability to defend yourself is simply represented by a number. The higher the number, the more able you are. The problem with this is that while a high difficulty implies skill of being a good fighter it leaves things open to problems. For example, the natural 20 in D&D happens once every 20 rolls and is generally an automatic hit, but against a someone that good at defending against you your odds of hitting may be much less. It also leads to situations where someone will get hit when really they shouldn't and the terrifying fight then becomes less so..
Damage Has Issues Too
Defense is, in fairness, probably less of an issue than this. Someone getting hit despite a high difficulty and improbable chance of being hit is likely just having a bad day. Damage though is weird. For one thing, the human body doesn't really handle damage in the fashion that numbers can represent. It's the old fighting game problem where someone is perfectly fine, or at least able to continue, after getting slammed through a building but a light slap to the wrist drops them from the fight.
Now, hit points in a lot of systems aren't supposed to represent how healthy someone is but rather how good they are at avoiding a blow from being crippling or fatal, but that doesn't always work either. Knives are generally a very low damage item in RPGs. It makes sense in a certain train of thought because a knife is more of a maiming weapon than a killing weapon. The one knife stab = one death is very rare. More often you get four or five stabs in and let the person bleed out. However, knives are very good at crippling people, and if someone gets you once with a knife odds are they're going to get you 2-3 more times before you can really react to anything. But this is almost impossible to represent with the kind of systems that table top games can use.
A Dance of Intricacies
In effect, the problem with representing combat is that it is a dance of intricacies. So many factors come into play that it is ridiculous to expect to code for them all and still have the system be intelligible. Reach, speed, strength, durability, skill all come into effect and that is before we count for what weapons bring to the table and how they interact with each other. Some systems (*cough*shadowrun*cough*) account for more of these things than others, but it is always at the cost of slowing things down.
And yet, excitement
And yet, I find myself really looking forward to seeing how lightsaber combat, or melee combat in general, works out in the new Star Wars RPG. See the game's dice mechanic looks like it could make for a very interesting combat system in that regards. Everything is rolled for, but it is done with speed because to make any roll you need good dice (dice that determine how successful you are) and bad dice (dice that determine how successful your opponent is.) The dice then have 3 reslts: success/failure, advantage/threat, and triumph/despair. What this means is that an attack could fail, but you still get an advantage out of the exchange which can help on your next roll and keep the fight going in your favor. Alternatively, a skilled defense could leave an opening for a strong follow up attack.
It should be interesting, and if it isn't, I will just wait for the fan hacks to come out. Maybe I'll make one myself.