Starting a new thread so as to not derail the excellent "simple or simulation" thread. This is an outline of my homebrew system for your comment and review.

Four Core Attributes. Each Attribute has a Skills List from which players choose and upgrade their powers. Proficiency skills are purchased once, "active" skills can be purchased twice to gain more powerful abilities. Skills can be added ad hoc with GM approval to fit character concepts. Generally, they should be broad categories like "Acrobatics," "Fire Magic," "Brute Force," and "Wilderness Survival." Actual stunts, spells and maneuvers using Skills are made up on the fly.

The Attributes are Slip for agility, speed, and guile; Beef for strength, endurance, and machismo; Brains for logic, deduction, and reason; and Sense for perception, practicality, and emotional intelligence. Your score in an attribute determines whether you can purchase skills from its list and how powerful they are.

Each Attribute is tied to a Save and to a Social approach and to a kind of motivation. When making a social roll, you add your bonus in that approach, as well as the modifier for your motive's Attribute. Ex: You want to lie about an incoming allied army to intimidate the commander of an enemy force. Your roll will be Deception, which is normally based on Slip, but since your goal is to frighten or threaten you'll use your Beef modifier (attached to Intimidation) along with your Deception bonus. The enemy's roll would be modified by his Deception bonus and whatever attribute modifier matches his reason to disbelieve you; for example, if he has done the math and does not believe your allies can reach him in the time you claim, he'll use Brains.