Before MUDs there was Meow....and it did not originally mean "Moral Equivalent Of War" as far as I know.

[url]http://wikibin.org/articles/meow-wars.html[/url]

My sympathies were with Grillo the Clown there although at the time I found Grillo annoying.

[Without rules, could it have been considered a proper sandbox? Ask a cat? Sorry, I couldn't resist.]