Ygg mechanic-less rules?

I definately want mechanics Mike.

My ideal plug in mechanic mechanic I'm looking for here is one where you can use keywords as a kind of shorthand for the detailed descriptions and system specific descriptions.

Schematically it would look like this:

[Keyword Based Mechanics] - magic spells, abilities, skills(?)
|
| (keyword)
v
[Keyword -> Conventional Mechanics "mechanic"]
|
| (conventional mechanic)
v
[Conventional Mechanics] - stats, combat system, combat skill

For example, instead of writing "Fireball, so and so much damage, this and that range, that and that casting time, that and that level, this is how it looks like blah blah blah" the keyword version might be: "Fireball, spell of medium efficiency"

If magic and abilities are written this way we save a lot of time writing it and reading it. It can also be woven into, or extracted from a story (e.g. prose text).

The difficulty is that what we're using isn't loss-less compression here. We lose info in the process. So somehow we (or rather "I") have to make a system where the "decompressed" mechanics are pretty consistent and acceptable. Another important thing is to motivate it so that people find this method acceptable.

A side benefit is that we can use a single keyword and decompress it into similarly acting but differently motivated powers. For example the pathlessness which could be a spell of confusion cast upon the persons entering the forest, or the trees actually moving.

What's interesting is that if we use keywords as our base for things, then it might be easier to make plot decisions first and then retroactively fit them to powers. If we are bound by the usual rather well defined powers (let's say we KNOW it has to be a "spell of confusion") we can't as easily puzzle the story together.

So two uses:
1. Shorthand
2. Flexible retconning powers

For the second, consider superhero comics where the origins of powers many times are retconned into something different. If a certain power was codified with its origin (like most spells are), it's hard to use this very powerful plot device. (If I say it's a fireball in AD&D, I can't change it to be a ball of demonic fire later, for example)