RPG Taxonomy

I don't think taxonomy is the right word here, maybe you can help me out with a better one. I think it would be cool to have an extensive look at the various approaches to the fundamental RPG situations. I'm sure parts of this already exist. For example, it seems Forge gamers have spent a lot of energy thinking about different mechanical approaches to Task Resolution in RPGs. I remember the 2e era D&D book Player's Option: Spells & Magic went into various systems of handling magic- spell points, at will, Vancian, etc.

But I would be fascinated with a book, or maybe a wiki would be more appropriate, that systematically looks at these common RPG elements and how you might approach them, and how they have been approached historically.

Lets take saving throws as an example: First what do you call this? Last Ditch, maybe. And how might it be/has it been handled?

1. A general buyout where players have a kind of trump card or fate point-- Did Marvel Super Heroes do this? How about Savage Worlds?
2. A general "luck" roll equal to all characters of all abilities-- examples?
3. A more general roll modified by ability. So, the more dexterous characters, regardless of archetype, are more likely to dodge a fireball-- Norman, you said C&C's SIEGE system is like this?
4. A general roll modified by severity, i.e. how Last Ditch it is-- Delta's system that Chris kindly pointed out.
5. A general roll modified by archetype. So, wizards are considered more resistant to magic-- Swords & Wizardry
6. A more specific roll based on archetype. So, wizards are considered more resistant to wands, spells and petrification, but less so to breath weapons-- classic D&D. Jeff lays out the classic D&D save categories here.

The last might be considered a roll modified by archetype and severity, but I think there is a distinction between Delta's idea of severity and that of save category types. What I mean is, you could have equally severe categories, which you felt different archetypes should have different chances at surviving. Also, traditional D&D seemed to have mixed feelings about this, thinking Death Ray from a wand and Death Ray from a magic-user, though equally instantaneously severe, were somehow differing in survivability. (unless I'm misunderstanding, did wands, staff, rods apply only if there was no more specific save category?)

This is why doing this is really interesting to me, when you start trying to categorize and lay something out in a system you are forced to encounter dimensions you hadn't seen before. When I started the numbered categories above I was working with the general assumption that they would progress from more abstract to more specific. In actuality, the different ways games have handled Last Ditch mechanics vary in different dimensions: the actor (wand, creature), those being acted upon (ability, archetype, experience), and severity (poison vs charm person).

One interesting thing this tells me is that we have competing features in our minds for what makes something more "realistic" for us. As DIY DMs we may feel that abilities seem much more important in the scheme of Last Ditch things than archetype or vice versa. And this is separate from how the mechanics play out in the game system. And these can be deviously hard to predict. Trollsmyth has a great post on trying to achieve certain goals through different mechanics (bonuses vs dice rolls).

Although, there may be general rules we can say are true, for example, the more of these categories a Last Ditch mechanic tries to incorporate the more complex it becomes. But then, perhaps that complexity can be "cooked in" or moved around various places in the system.

And Last Ditch is just one example. In trying to categorize and systematize all RPG situations, surely we would encounter some we hadn't even noticed. I think one example is the generation of hireling traits, which I've mentioned before. That is typically considered part of pre-play preparation, but that I've brought into play and handed off to players at Jeff Rient's suggestion.

So, hope that is more productive than my last post on saves.