Elon Musk's 'x.com' game?

On July 14 Elon Musk has announced on twitter the launch of x.com website:

Few hours later this tweet was followed by:

And then he twitted a mysterious phrase:

When entering http://x.com you get only a blank page with a letter x on it. URLs of type http://x.com/abc (with any symbols instead of abc) lead you to similar page, but with letter y instead of x.

Could this be some kind of a game by Elon Musk, where you should find the right url(s)?