I've never heard of 40-40 in game, but it sounds awesome.
I invented a game called Jungle, which follows the hide-and-seek (Which we shortened to "Hido/Hydo, because we're dope yo'!") formula, but you need a very long grass field for this. One plays the Lion and must catch everyone. Everyone is crawling in the field so you don't know who is near.
Also, playing Tracker at one of the N-E meets was genius.