http://www.thefeature.com/article?articleid=100501&ref=751478

Problem with April Fools is you can never quite decide what's real and what's an elaborate spoof. However I think this is real, and it's definitely cool...

"some items only appear at certain places, at certain times." For example, Castelli cites the creatures in the game: "We used the map to give creatures some interesting behavior. Some creatures only hunt at night. Some hang around close to parks." If a player wants to find that creature, they'll have to travel near a park in the evening hours."