Elements of a RPG

[The Hive Custodian]

I've been trying to figure out what the elements of a roleplaying game are, in the hopes that it will help with system design. So far, I have these:

Character creation. A system for describing and representing characters in the game.
Action resolution. Game mechanics, rules or guidelines for how results are determined in the game.
Setting. The world where game events take place.
Player roles. What each player is responsible for, e.g., the GM and player system.Obviously none of these can be built completely isolated from the others. However, I believe some measure of modularity and interchangeability is possible and beneficial.

Does this sound about right? Do these sound like the elements of a RPG? Are there any major elements that I missed?

Note that my question is not so much "what elements make an RPG an RPG as opposed to something else?" as "if you were to design a complete RPG, what elements would you need to take care of?"

[nightinverse]

Those are the major elements, through I abstracted connective rules and content - the material which binds the four bullets together - out the last time I worked on a system. If you remove them a step, you'll probably find you've generated some comparatively needless complexity, but it may help with a modular system to have the connective and interactive elements between the groups separate from them.