Everyone is falling. And fighting. The object of the game is to hit the ground last. It's not much of a goal, but it's all you could think of on the way down.
One player deals the cards, while the other players fall. There are no turns; everyone is playing at once. Players can play cards on each other, or on themselves. These cards are called "riders," and they change how the dealer will deal. A "Hit" means "Give me two cards." A "Skip" means "Don't give me anything." And so on. Those Skips come in really handy at the end of the deck, when the dealer starts handing out the Ground cards. Catch a Ground card, and you're dead.
Falling is a real-time game, it takes as long to play as it takes to deal a deck of cards at a leisurely pace. You could literally play in less than a minute.