A-Z challenge: G for Grimworld and game worlds and settings(oh the schedule)

I think that this blog challenge for me is a failure. Still, even though I don't keep up like the rest of participants, I decided to hang on. For my own amusement.

So, G for Grimworld. Grimworld was basically a fantasy setting/project, but when I thought about it I found that it's mere a toolbox. Or a synonym for my own fantasy toolbox.

I mean, I won't ever write any detailed information about Grimworld. It grows and advances when I add items, or when I Game master it (if I ever will, that is). So, what's the point about this Grimworld, what is a fantasy setting but isn't?

Here are key points, I think make Grimworld what it is and make it useful for myself.

If player knows, that his character is in this mysterious fantasy world and you tell the player, that it is a mysterious place to be, even for an inhabitant (character). You can easily explain this by making character someone, who has been only in one place for his entire life. Farmer's son whose fate lies in heroism, city guard who has to venture to unknown lands to rescue his lord, mage's apprantise who has to show his worthiness to his master...
So, when player starts the game, he knows the location where his character is from. Actually, as Grimworld is a toolbox, player character could if he wanted write his own past including his village or tribe he lived in. It's Game masters job to approve or fix the background story.
But the point is, even players can make additions to the world via their characters and I can take notes thus making the world and setting larger.

Same goes with me as GM. I need a forbidden swamp? Yep, there it is and someone from game world knows where it is, so it has always been there. Tribe of cannibal hobbits, done.
The world has as many aspects, adventures, races, tribes, monsters, magical items as I want. That's the key of Grimworld. My ideas are not restricted in any way by setting, nor my ideas kill canon or logic of any particular game world/setting.

That is the reason why I usually like my own settings. I can do what ever I want to do, without actually changing pre written setting. I know, that games are made for you for your amusement, and no one is telling you that you cannot change settings. But somehow I feel like violating the original author if I make too many changes (that is the reason, for example, why I always in Vampire: the Masquerade games use fictional city, not city based on real life or city which is presented in V:tM sourcebooks).