Here are the rules to "I Spy" as I understand them:

1) A person is selected to be "It".
2} "It" thinks of some thing or some person
3) "It" says the set sentence "I spy etc" adding the letter that
   is at the beginning of the word [what he or she is thinking]
4) One at a time people try to guess what "It" was thinking about
5) "It" says 'no' if the guess is wrong {or in this cyberspace
   version doesn't respond if the guess is wrong}
6) "It" says 'yes' {or writes a post to this thread}when a person
   guesses right.
7) The person who guesses right becomes the new "It" and the game
   is supposed to start all over again.

I'm curious, is this game not known outside of the USA?