Friday, June 5, 2015

Deep Analysis: Rpg mechanics model and the Old School effective range

What is the logic behind rgp systems
and Old School mechanics?

An rpg system is a mechanics model that uses mathematics, statistics and logical procedures in order to guide its participants to create their storytelling experience. Whatever be the system used, it will have a mechanical procedure to provide answers to conflict resolution and options for world and story building. Be it a very simple system, like Cthulhu Dark, or a complex one, like HERO or GURPS, all systems have a model that it uses to resolve conflicts and present new possibilities of play.

And because it is a mechanics model, every rpg system has an optimal range of application and action – the kind of storytelling experience that it is trying to emulate, an 'optimal targeted range', or 'effective range' per se. And when you try to go beyond that range, the system starts fumbling, working in a faulty manner and needing some overhauling by the participants, giving it house rules and addends.

It is very easy to see the limitations of an rpg system. You just need to stretch it a little bit and try to use it in a different context than usual. For example, if you try to use Cthulhu Dark as a deep and strategic combat simulation, the system will just not work well. The same poor result will happen if you try using the d20 system to play an investigative horror game, with deadly free form combat and focus on gathering clues. Or if you try using the GURPS system's basic rules to play anything that is not realistic.

This does not mean that you can't use those systems to play these kinds of games. You can play everything with anything, and the objective with an rpg system is to provide rules that will help your group to have fun. The thing is that going beyond the targetted range of a system will probably break it and create awkward situations. You may have to deal with many modifiers and having to roll dozens of dice, making every single action extremely slow. Or maybe the stats will be so high that the bookkeeping in game will be unbearably boring. Or maybe the game just gives no support to some actions, like, for example, using tactical combat in Cthulhu Dark. When a system goes beyond its projected scope of action resolution, it basically - borrowing a term from the electronic games domain – glitches. And it normally takes a lot of effort to essentially create a 'mod' for the game, where those glitches are fixed or new rules are added.

The Old School Mechanics Model

After discussing about the overall aspects that exist in all systems, I'd like to ellaborate on what is the model which Old School Systems (and I'm referring more specifically to the Old School D&D affiliated games) are based on and what would be their intended effective range.

Old School games are based in classic sword and sorcery fantasy – the likes of Conan and Lord of the Rings, besides european mythological and legendary tales, such as the Arthurian Cycle, the Beowulf tale and the Nibelungen Lied. These are the fiction that Old School Games try to emulate – and more than just emulating those tales, as I discussed previously here, the Old School genre tries to emulate the challenges of those stories: delving into a creature's lair, fighting creatures of darkness, dungeoncrawling in search of treasures, hoarding treasure and becoming a renown adventurer.

So, if the objective in an Old School game is to emulate those actions found in sword and sorcery fantasy, the mechanics themselves are geared towards hitting that target. If we take a look at Old School D&D (which had its mechanics based in wargaming rules that developed further to accomplish one-on-one combat and action resolution) and analyse its core mechanics – the hit roll, armor class value, hit die, damage and saving throws – we see that they all fall into a precise escale of resolution. Besides damage and hit points, all other rolls are based on a 1 to 20 scale, more or less. The hit roll, integrated in the THAC0 (to hit armor class 0), went from 20 to 0. Also, the saving throws, were numbers that ranged from 20 to 2. The same idea of a matrix of resolution that falls into this '20' escale.

And adding to that, Old School rolls were devised thinking humanoid creatures, and specially the player characters. For example, the Armor Class system took its base on humanoid characters wearing armor. An AC 3 [17] was equivalent to a human wearing plate. So, if you see a monster with AC 3 [17], that would mean that this creature was 'as hard to harm as a human wearing plate'. 

At the same logic, saving throws were based on how heroes could survive impossible odds, like being struck by a dragon's breath or resisting a medusa's petrifying gaze. Normally, if you are a normal human and were afflicted by such attacks, you'd basically be dead. But, if you are a hero, maybe you can survive. That is the reason behind the saving throw, and that is the reason why being a 1 st level character you have such a low chance of resisting danger – because the whole Old School system is geared towards that 1 to 20 scale. At first level, you are a 'newbie hero', and it is hard to do heroic stuff yet. At max level, you are a 'veteran hero', and you do things very well – but you may STILL die. You are just better at surviving than a 1st level character.

1st ed AD&D Dungen Master Screen
Hit roll and Saving Throws values
That is the Mechanics Model for Old School games – humanoid sword and sorcery heroes. All statistics are modelled on those figures. The target for Old School games was emulating those old tales and legends, focusing on exploration and overcoming challenges, and the effective range of its rules was heroic dungeoncrawling the likes we see in Conan. 

With that said, maybe I may answer the question I asked in my post about giant creatures. The reason why  it gets sometimes silly when you fight creatures the size of buildings in Old School Systems is because fighting creatures of that size and power is beyond the effective range of their mechanics, even when they just give random stats to giant monsters.

But in the end, every gaming table is different, and with good houserulling you may ampliate the effective range of a system. What do you folks think of it? How do you people overcome the limitations of a system? Do you think they exist at all? I'm curious to hear what you think of it.

Until then,


1 , entering Acererak's Tomb. A great drawing by Brian 'Glad' Thomas.
2 is taken from the AD&D's 1st edition dungeon master screen


  1. I am also evaluating different RPG systems, and like your approach. If you're still open to discussion (or if you have another post elsewhere) I would like to know how far you have proceeded and if you came up with any way to compare them qualitatively or quantitatively?

    1. That post was by me.... My ID was not linked to my post above, but it should be on this reply.