Character options may be reduced to:
-Attack (roughly rounding up anything that makes direct damage or imposes a condition that will make direct damage greater or easier to do, including straight killing another character)
-Defense (including anything that either reduces, transfers or nullifies direct damage, like armor, healing, regeneration, etc)
-Movement (as in everything the character can do to get a positional advantage, get out of a positional disadvantage, or go through an obstacle)
-Perception (all sources of somewhat immediate external information the character has at their dispossal like common senses, darkvision, supernatural senses, machine-like sensors, etc)
-Knowledgement (all sources of information the character may reach, like memory, books, gathering information rolls, investigation, etc)
-Subterfuge (anything the character can do to avoid direct confrontation like stealth related skills, invisibility, disguise
-Social (all the ways the character can convince others to do their bidding as diplomacy, leadership, persuassion, lying, performance, etc)
-Creation (whatever the character can do to make up tools or resources)
There are more rare options like the skills to teach skills to other characters and more, but basically whenever a GM makes a player roll the dice or a mechanic is called up to solve things, it's about one of this options.
I made this categorization a while ago and thought it could be used RAW as character stats but after a few tests I had to recognice they didn't work that way. However this still seems to be somewhat useful when it comes to balancing character skills/powers/items/special abilities.