Well, Thor is the Norse god of war, and thus would seem to make an intimidating Gamertag. Unfortunately, at least one other person had thought of this before me, and so I was left with a choice: Look like an idiot and add a bunch of random numbers after my name (Thor4122, etc) or add a prefix. I had already tested a couple of other Gamertags for availability in the meantime, and one of the suggested prefixes to one of those was the word "Enigmatic." I liked both the sound of the word and the meaning, and so I became EnigmaticThor. Plus, it's almost guaranteed not to be taken anywhere else, either.