Let me Explain The elder scrolls "Generations"
First generation - The main way to level up is to kill things were XP is gained by Each Kill. There are and Attributes that get leveled up and changed as you progress. Very Large, but possibly under detailed games.
Second generation - Main way to level up is to increase your Major or Minor Skills. Attributes and skills level up, but skills are capped at 100 unless using enchanted items or such. Not as Large Scale as it's predecessors but much more detailed with all unique NPCs that you can interact with.
Third Generation - Maybe Skyrim will turn the way we see TES upside down