So my question: Which RPGs--especially fantasy RPGs--already do this well, and in a way that isn't overly complex? Preferably still requiring just one role. Please give a brief explanation of how it works.
Mythras does this pretty well. It continues from the RuneQuest base (it is the re-branded RuneQuest 6). In terms of PC/NPC and creature modelling, it uses hit locations, hp and armour points per location. Below is an example with average human HP in each location and a selection of armour. In this case the character is wearing a half-plate helmet (5 points), scale hauberk (chest and abdomen 4 points) with padding on limbs (2 points). The strongest manufactured armour is usually around 8 points. Creatures may have natural armour which protects in the same way.
| Head (5 / 5) | |
Right Arm (2 / 4) | Chest (4 / 7) | Left Arm (2 / 4) |
| Abdomen (4 / 6) | |
Right Leg (2 / 5) | | Left Leg (2 / 5) |
The second number is hp per location, there is no general hp in the system, and hp does not increase although of course stronger armour can be worn. Weapon damage varies from a dagger (1d4+1), to a spear (1d8+1) up to a 2h monster like a great axe (2d6+2). Humans can have damage modifiers based on their strength and size which add to weapon damage.
As you can see, this PC is pretty well protected against a dagger, does ok against an average hit from a spear but will start to take minor wounds in the vitals from stronger hits. An average hit from a great axe though will easily disable an arm and take most of the hp from a body or head hit. When a hit location goes to zero, it is considered a "serious" wound, where the victim becomes stunned and may lose the use of that location - ie. they fall, or they drop a weapon. If a hit location goes negative equal to its starting hp, that is a "major" wound which will take most characters and creatures out of the fight. Such a hit may sever a limb, decapitate, or even chop the body in two.
Attacking and defending is resolved using a skill Vs skill roll (the combat skill of the combatants). In simple terms, if the attacker succeeds with their attack roll, and the defender fails their parry, the defender gets hit. This is no different from standard BRP resolution.
A Mythras innovation is the introduction of Special Effects, which in the above example would allow the attacker to use one special effect of their choice because they beat the defender. Special effects are things like Tripping attempts, impaling with an impaling weapon (such as a spear), choosing a location to hit (by default hit location is rolled randomly), disarming attempts and so on. More powerful special effects are available on a critical success. Special effects are available to both attacker and defender, so if the defender won in this case, they could choose an effect to use against their attacker such as a trip or disarm and so on.
Special Effects are where most of the fun in the combat system is. Starting from the BRP base, special effects brings to combat a dynamic sense of pressing and resisting an advantage or opening, so that combats tend to be decided by special effects rather than HP attrition. Hit points are generally low anyway, but special effects add excitement to combats which other BRP games tend to lack.
The pain points in the combat system for players generally are - Action Points, these in practice tend to work well but are initially the cause of some worry. It is easy simply to use the option for fixed actions (2 per round). The large number of special effects avaiable can also bamboozle new players (and GMs) but this analysis paralysis is actually fairly easily dealt with. It works best with a small number of PCs and opponents, in settings of middling to low-armour, although I have seen it work at very high level and it still seems playable.
The Mythras Imperative SRD is free and maintained online
Mythras Imperative System Resource Document
This is better understood as a rules-sampler as it is only the core of the rules, it misses out most of the magic traditions, the creature chapter, and much of the GM material. Nevertheless it is enough to run a test game to get a feel for the system. The more traditionally-focused Mythras Classic Fantasy (imperative) is also available from the same website and is even more of an extensive rules sample.
There is a detailed combat example on Runeblogger's website:
Samurai duel: a combat example with Mythras
The combat breakdown uses a video of a samurai duel, viewable on the page.
